Thanks for all the help –?and the quick fix. I decided to just update my Mac to Monterey, and the problem is indeed not there in Safari 15.
There is another related one, however, and I’ll pivot this thread to that. This problem, or rather slight annoyance, is also not present in Chrome, but is there in both Safari 15 and mobile Safari.
Instead of just highlighting the button I click, it also highlights the entire Gutenberg block (?). So instead of looking like this:
https://snipboard.io/lBXMxT.jpg (CHROME)
it looks like this:
https://snipboard.io/ucgfxy.jpg (SAFARI)
Definitely not an important problem, but certainly not optimal either. Is there a quick fix for this?