diff --git a/tests/e2e/with-integrations.test.ts b/tests/e2e/with-integrations.test.ts
new file mode 100644
index 0000000000..5df1582ff9
--- /dev/null
+++ b/tests/e2e/with-integrations.test.ts
@@ -0,0 +1,56 @@
+import { expect } from '@playwright/test'
+import { test } from '../utils/playwright-helpers.js'
+
+test('Renders the Home page correctly', async ({ page, withIntegrations }) => {
+  await page.goto(withIntegrations.url)
+
+  expect(page.locator('body')).toHaveText('Hello World')
+})
+
+test.describe('Should clear stale functions produced by previous builds by @netlify/plugin-nextjs', () => {
+  test('Serverless functions', async ({ page, withIntegrations }) => {
+    const response1 = await page.goto(new URL('/test/serverless/v4', withIntegrations.url).href)
+    expect(response1?.status()).toBe(404)
+
+    const response2 = await page.goto(new URL('/test/serverless/v5', withIntegrations.url).href)
+    expect(response2?.status()).toBe(404)
+  })
+
+  test('Edge functions', async ({ page, withIntegrations }) => {
+    const response1 = await page.goto(new URL('/test/edge/v4', withIntegrations.url).href)
+    expect(response1?.status()).toBe(404)
+
+    const response2 = await page.goto(new URL('/test/edge/v5', withIntegrations.url).href)
+    expect(response2?.status()).toBe(404)
+  })
+})
+
+test.describe('Should keep functions produced by other build plugins', () => {
+  test('Serverless functions', async ({ page, withIntegrations }) => {
+    const response1 = await page.goto(
+      new URL('/test/serverless/integration-with-json-config', withIntegrations.url).href,
+    )
+    expect(response1?.status()).toBe(200)
+    expect(await response1?.text()).toBe('Hello from /test/serverless/integration-with-json-config')
+
+    const response2 = await page.goto(
+      new URL('/test/serverless/integration-with-json-config', withIntegrations.url).href,
+    )
+    expect(response2?.status()).toBe(200)
+    expect(await response2?.text()).toBe('Hello from /test/serverless/integration-with-json-config')
+  })
+
+  test('Edge functions', async ({ page, withIntegrations }) => {
+    const response1 = await page.goto(
+      new URL('/test/edge/integration-in-manifest', withIntegrations.url).href,
+    )
+    expect(response1?.status()).toBe(200)
+    expect(await response1?.text()).toBe('Hello from /test/edge/integration-in-manifest')
+
+    const response2 = await page.goto(
+      new URL('/test/edge/integration-not-in-manifest', withIntegrations.url).href,
+    )
+    expect(response2?.status()).toBe(200)
+    expect(await response2?.text()).toBe('Hello from /test/edge/integration-not-in-manifest')
+  })
+})
diff --git a/tests/fixtures/with-integrations/netlify.toml b/tests/fixtures/with-integrations/netlify.toml
new file mode 100644
index 0000000000..4c48c42e10
--- /dev/null
+++ b/tests/fixtures/with-integrations/netlify.toml
@@ -0,0 +1,2 @@
+[[plugins]]
+package = "/plugins/create-other-functions"
diff --git a/tests/fixtures/with-integrations/next.config.js b/tests/fixtures/with-integrations/next.config.js
new file mode 100644
index 0000000000..8d2a9bf37a
--- /dev/null
+++ b/tests/fixtures/with-integrations/next.config.js
@@ -0,0 +1,8 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  eslint: {
+    ignoreDuringBuilds: true,
+  },
+}
+
+module.exports = nextConfig
diff --git a/tests/fixtures/with-integrations/package.json b/tests/fixtures/with-integrations/package.json
new file mode 100644
index 0000000000..4c3fe8a3ac
--- /dev/null
+++ b/tests/fixtures/with-integrations/package.json
@@ -0,0 +1,13 @@
+{
+  "name": "with-integrations",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "build": "next build"
+  },
+  "dependencies": {
+    "next": "latest",
+    "react": "18.2.0",
+    "react-dom": "18.2.0"
+  }
+}
diff --git a/tests/fixtures/with-integrations/pages/index.js b/tests/fixtures/with-integrations/pages/index.js
new file mode 100644
index 0000000000..c76736b1d1
--- /dev/null
+++ b/tests/fixtures/with-integrations/pages/index.js
@@ -0,0 +1,7 @@
+export default function Home() {
+  return (
+    <main>
+      <h1>Hello World</h1>
+    </main>
+  )
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/integration-in-manifest.mjs b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/integration-in-manifest.mjs
new file mode 100644
index 0000000000..fa0e08423a
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/integration-in-manifest.mjs
@@ -0,0 +1,3 @@
+export default function handler() {
+  return new Response('Hello from /test/edge/integration-in-manifest', { status: 200 })
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/integration-not-in-manifest.mjs b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/integration-not-in-manifest.mjs
new file mode 100644
index 0000000000..6ae83beeae
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/integration-not-in-manifest.mjs
@@ -0,0 +1,7 @@
+export default function handler() {
+  return new Response('Hello from /test/edge/integration-not-in-manifest', { status: 200 })
+}
+
+export const config = {
+  path: '/test/edge/integration-not-in-manifest',
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/manifest.json b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/manifest.json
new file mode 100644
index 0000000000..e666c230ed
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/manifest.json
@@ -0,0 +1,24 @@
+{
+  "functions": [
+    {
+      "function": "next-runtime-v4",
+      "name": "next-runtime-v4",
+      "path": "/test/edge/v4",
+      "generator": "@netlify/plugin-nextjs@4.41.3"
+    },
+    {
+      "function": "next-runtime-v5",
+      "name": "next-runtime-v5",
+      "path": "/test/edge/v5",
+      "generator": "@netlify/plugin-nextjs@5.3.3"
+    },
+    {
+      "function": "integration-in-manifest",
+      "name": "integration-in-manifest",
+      "path": "/test/edge/integration-in-manifest",
+      "generator": "@netlify/some-integration@1.0.0"
+    }
+  ],
+  "layers": [],
+  "version": 1
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/next-runtime-v4/next-runtime-v4.mjs b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/next-runtime-v4/next-runtime-v4.mjs
new file mode 100644
index 0000000000..049598094a
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/next-runtime-v4/next-runtime-v4.mjs
@@ -0,0 +1,5 @@
+export default function handler() {
+  return new Response('Hello from edge functions generated by @netlify/plugin-nextjs@4', {
+    status: 200,
+  })
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/next-runtime-v5.mjs b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/next-runtime-v5.mjs
new file mode 100644
index 0000000000..c9d66887dc
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/edge-functions/next-runtime-v5.mjs
@@ -0,0 +1,5 @@
+export default function handler() {
+  return new Response('Hello from edge functions generated by @netlify/plugin-nextjs@5', {
+    status: 200,
+  })
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/integration-no-json-config.mjs b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/integration-no-json-config.mjs
new file mode 100644
index 0000000000..ebde11d0db
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/integration-no-json-config.mjs
@@ -0,0 +1,7 @@
+export default function handler() {
+  return new Response('Hello from /test/serverless/integration-with-json-config', { status: 200 })
+}
+
+export const config = {
+  path: '/test/serverless/integration-with-json-config',
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/integration-with-json-config.json b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/integration-with-json-config.json
new file mode 100644
index 0000000000..e8c468d4a8
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/integration-with-json-config.json
@@ -0,0 +1,7 @@
+{
+  "config": {
+    "name": "Some integration",
+    "generator": "@netlify/some-integration@1.0.0"
+  },
+  "version": 1
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/integration-with-json-config.mjs b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/integration-with-json-config.mjs
new file mode 100644
index 0000000000..cdc63ea00c
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/integration-with-json-config.mjs
@@ -0,0 +1,7 @@
+export default function handler() {
+  return new Response('Hello from integration generated serverless function', { status: 200 })
+}
+
+export const config = {
+  path: '/test/serverless/integration-with-json-config',
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v4/next-runtime-v4.json b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v4/next-runtime-v4.json
new file mode 100644
index 0000000000..bd03425470
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v4/next-runtime-v4.json
@@ -0,0 +1,6 @@
+{
+  "config": {
+    "generator": "@netlify/plugin-nextjs@4.41.3"
+  },
+  "version": 1
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v4/next-runtime-v4.mjs b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v4/next-runtime-v4.mjs
new file mode 100644
index 0000000000..a511b8aebb
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v4/next-runtime-v4.mjs
@@ -0,0 +1,9 @@
+export default function handler() {
+  return new Response('Hello from edge functions generated by @netlify/plugin-nextjs@5', {
+    status: 200,
+  })
+}
+
+export const config = {
+  path: '/test/serverless/v4',
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v5.json b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v5.json
new file mode 100644
index 0000000000..5745d57acd
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v5.json
@@ -0,0 +1,6 @@
+{
+  "config": {
+    "generator": "@netlify/plugin-nextjs@5.3.3"
+  },
+  "version": 1
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v5.mjs b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v5.mjs
new file mode 100644
index 0000000000..771a820020
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/functions-internal/next-runtime-v5.mjs
@@ -0,0 +1,9 @@
+export default function handler() {
+  return new Response('Hello from edge functions generated by @netlify/plugin-nextjs@5', {
+    status: 200,
+  })
+}
+
+export const config = {
+  path: '/test/serverless/v5',
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/index.js b/tests/fixtures/with-integrations/plugins/create-other-functions/index.js
new file mode 100644
index 0000000000..495fab67a3
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/index.js
@@ -0,0 +1,14 @@
+const { cp } = require('node:fs/promises')
+const { join } = require('node:path')
+
+exports.onPreBuild = async function onPreBuild({
+  constants: { INTERNAL_FUNCTIONS_SRC, INTERNAL_EDGE_FUNCTIONS_SRC },
+}) {
+  // copying functions:
+  //   - mocked functions to represent stale function produced by @netlify/plugin-nextjs (specified by `generator`) for v4 and v5 of runtime
+  //   - mocked functions to represent functions produced by other build plugins (either specified by `generator` or missing `generator` metadata)
+  await Promise.all([
+    cp(join(__dirname, 'edge-functions'), INTERNAL_EDGE_FUNCTIONS_SRC, { recursive: true }),
+    cp(join(__dirname, 'functions-internal'), INTERNAL_FUNCTIONS_SRC, { recursive: true }),
+  ])
+}
diff --git a/tests/fixtures/with-integrations/plugins/create-other-functions/manifest.yml b/tests/fixtures/with-integrations/plugins/create-other-functions/manifest.yml
new file mode 100644
index 0000000000..2e34b6ffbc
--- /dev/null
+++ b/tests/fixtures/with-integrations/plugins/create-other-functions/manifest.yml
@@ -0,0 +1 @@
+name: 'simulate-integration'
diff --git a/tests/utils/create-e2e-fixture.ts b/tests/utils/create-e2e-fixture.ts
index eab7dc4f79..4ca773ebde 100644
--- a/tests/utils/create-e2e-fixture.ts
+++ b/tests/utils/create-e2e-fixture.ts
@@ -353,6 +353,7 @@ export const fixtureFactories = {
     createE2EFixture('cli-before-regional-blobs-support', {
       expectedCliVersion: '17.21.1',
     }),
+  withIntegrations: () => createE2EFixture('with-integrations'),
   yarnMonorepoWithPnpmLinker: () =>
     createE2EFixture('yarn-monorepo-with-pnpm-linker', {
       packageManger: 'berry',