The "Use same aspect as pixels" button is a checkbox that when off gives an accurate depiction of the print size when zooming. This naming is really confusing. My proposal is to make this functionality clearer by renaming the button "Print Size" and reversing the behaviour of the checkbox. So when its on, zoom is locked to print size and when its off its locked to the screen resolution.
In addition to the naming, it appears that this toggle only exists in the zoom widget and not available as an action, which means it does not exist in the "View" menu, and a hotkey cannot be bound to the toggle.
A possibly relevant merge request was started @ https://invent.kde.org/graphics/krita/-/merge_requests/1220
*** Bug 448076 has been marked as a duplicate of this bug. ***
Git commit c4dcbf9047febc10e73896584998089616e943c0 by Dmitry Kazakov, on behalf of Tom Tom Tom. Committed on 23/03/2022 at 12:35. Pushed by dkazakov into branch 'master'. Reverse functionality of aspectButton M +2 -1 libs/ui/KisView.cpp M +2 -2 libs/ui/kis_zoom_manager.cc M +1 -1 libs/ui/tests/kis_prescaled_projection_test.cpp M +1 -1 libs/widgets/KoZoomAction.h M +2 -2 libs/widgets/KoZoomWidget.cpp M +1 -1 libs/widgets/KoZoomWidget.h https://invent.kde.org/graphics/krita/commit/c4dcbf9047febc10e73896584998089616e943c0