Might be odd native browser behavior. But you didn’t tell us which browser this is.
Apologies about not including that, I’m using Google Chrome Version 104.0.5112.79.
Where does the emoji menu come from? My Chrome doesn’t have that.
It’s Chrome on the Mac. The issue mentioned happens in a vanilla contenteditable div so seemingly just a browser glitch as you mentioned.
Then I’d say this is not something ProseMirror is going to ‘fix’ – if a native editing action has a somewhat unexpected effect, that’s a browser issue, not a library issue.