Ah, always good to be reminded to start with a blank ~/.config/joplin-desktop/ (after having it backed up some way) in case of a rollback. I have read various instructions for such cases on this forum, but I would very much appreciate a complete guide in one place for all platforms.

Currently, I do all my experiments on the Mac, because rolling back is so easy there: just rename/move the ~/.config/joplin-desktop/ folder, copy the old Joplin version to /Applications/ (overwriting the newer version), run it, define the wanted configuration settings again (actually the most annoying operation is this procedure), copy the old userstyle.css and userchrome.css to the new ~/.config/joplin-desktop/ folder, exit Joplin, rerun it, and find that everything works again as it did before. And oh yes, the backup of the configuration can now be deleted.

I wouldn’t know how to downgrade on Windows or Linux. And mobile is completely dark matter to me.