Since I have been saying "macOS 26 Tahoe is fine I guess" I should probably mention that I have now discovered an intermittent failure mode where:
1. notification center stops showing the 'x' on hover on any notification after the first time an 'x' is clicked, until it is hidden and re-shown
2. baldur's gate 3 hangs immediately upon clicking 'play' in the launcher (and maybe some, but not all, other games also hang)
these symptoms are correlated and it's fixed by a reboot