I don't see any add-ons/extensions that can disable built-in shortcuts. I've tried setting permissions.default.shortcuts to 2, then restarted FF and refreshed the page, but it doesn't help.

At https://support.mozilla.org/en-US/questions/1367908 there is a solution that worked for me for over a year. Then I had to upgrade to Firefox 135 today and it stopped working. I see no other postings about this. Am I the only person who's driven nuts by not being to assign keyboard shortcuts intelligently?