A quick way to close all inline-diffs previously open in "status" window (:G)

[poige]

Not sure exactly but seems all the stuff manually open with =-keypress per file just keeps floating there until it's closed back.
Since patches tend to become larger it's non-practical to collapse them back one by one.

[tpope]

You can press < on a section header (Staged or Unstaged) to collapse all files in that section. Or use :e! to reload the buffer with all sections closed.

See also the sprawling discussion at #1563, which contains other ideas that haven't been implemented.