SUMMARY This is on Wayland at least. The video should be self-explanatory: while the Desktop Grid effect is ongoing, it temporarily blacks out the right portion of the screen. Unlike bug #440940, this doesn't happen at the end of the animation.
Created attachment 141613 [details] Desktop Grid with black areas
*** This bug has been marked as a duplicate of bug 440940 ***
*** Bug 443247 has been marked as a duplicate of this bug. ***