Oh man, this is driving me nuts just reading about it! Chrome and its fullscreen scaling shenanigans... classic.

This is 100% a Chrome bug. I've seen similar weird cursor stuff when you mix fullscreen with zoom it's like Chrome can't figure out where things actually are anymore.

Quick things to try that sometimes work:

1. Throw transform: translateZ(0) on the button (forces hardware acceleration)
2. Maybe will-change: transform
3. Could try pointer-events: auto but if clicks work, probably won't help

The fact that only the top component breaks is so bizarre. Sounds like Chrome's getting confused about stacking contexts when it's doing all that scaling math.

Does it happen in Edge too? If not, then yeah it's definitely just Chrome being Chrome.

Honestly though? You might just have to live with it or file a Chrome bug. I know that sucks but these super specific edge cases are usually not worth the time to hack around.

One random thing does it do the same thing with other cursor types? Like what if you set it to grab or crosshair instead of pointer?