I had previously reverted to 29 and skipped a few versions because of various problems, but back on track.
Tests:
Customizations which I lost when I reverted to 29 are back with no trouble.
Some of my customizations are now the default, others merely preserved the flag settings that 29 did not use.
Still not FLoCed ==> https://amifloced.org/

All previous complained about bugs fixed.
Not just complained here in the forum, used the feedback form with detailed technical observations.
https://www.slimjet.com/en/onlinefb.htm
I'd like it better if there were more communication about bug fixes.
Not a bug, but an OK undocumented change:
When closing the last window with a lot of tabs open, I get this little message box:

Note: I have Slimjet explicitly configured to clear history on exit, YMMV.
Doesn't show this when clearing history manually.
There was previously a bug related to memory handling that made it hang when closing the last window, but this feature doesn't seem to be a cover for that because it zips by quickly.
Is there a flag to suppress this message?
Edited to combine posts after testing.