The reason is that I am not sure what exactly the sentence is about:
(1) Display [… something …]
or
(2) Set [… something …]
I guess (1), but want to make sure in practice and I don’t seem to find the menu entry. If (1), for me it would have been clearer if instead of “set” it had been “setting”.
to execute the command, type it in: https://docs.gimp.org/3.0/en/gimp-help-search-and-run.html
on the bottom left corner you will see (default): 180.00˚ (flipped) I guess because the default (0°) put it as invisible
It’s the angle set with view->Flip & rotate->Rotate 180 … but I do not know why a “display” should actually set it to 180° … maybe a bug?