In two monitors, focus mode, normal mode will change size every switch

I use two monitors, one is 1080p, and one is 4k
if i put normal mode or focus mode in 4k, and the other mode in 1080p
then, I switch focus mode repeatly
Then, the mode in 4k will be bigger every switch
the mode in 1080p will be smaller every switch

I wish I express clearly.

First reproduce the issue with two monitors at 1080p and 4K, assigning normal mode and focus mode to different displays and switching focus mode repeatedly. Trace the focus/normal mode window sizing behavior; done means repeated switches no longer enlarge the 4K mode or shrink the 1080p mode.

Written by the indexing model from the issue text.