On Sun, Oct 17, 2021 at 09:14:39PM +0800, Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors wrote:
> 
> Move the cursor over a raised box, like the buttons in a customize
> buffer.  Parts of the cursor will remain in the box even after the
> cursor is moved out of the button.
> 
> I was told that this also occurs on macOS.
> 
> I've attached a patch that fixes the problem for me, but it hasn't been
> tested on macOS.

Hmm, your patch effectively undoes the change in

    Fix NS inset rectangle corners
    9ce3fdc461c9ec799ccbdc9281e392b0b77efd2b

I've attached my attempt to fix it. (Also not tested on macOS, but I
can't see why it wouldn't work there.)
-- 
Alan Third