Howdy,
Ancient Firefox user who went Chrome for a long time and have returned as of yesterday. Happy to be back, but routinely frustrated that textbox shortcuts like ctrl-b and ctrl-i on certain (but not all!) websites, per Firefox programming, triggers the bookmark sidebar / page info (respectively). In decades of computer use, these shortcuts have always always always meant applying bold and italic to highlighted text, making Firefox's functionality completely counterintuitive. I can honestly say I have never once used these shortcuts to intentionally pull up bookmarks or page info.
Having had a look around online it seems that the only ways to turn off these Firefox functions are either writing some javascript personally, or installing an extension which is not supported by Mozilla. As neither of these are especially palatable choices, and the existing regime is in defiance of 40ish years of keyboard convention, I'd like to propose the simplest of solutions: an option in Firefox's settings to turn off keyboard shortcuts.
That way, folks have the choice. If, like me, you find the defiance of keyboard convention frustrating, you'll have an option to turn it off. Or alternatively, if you like Firefox's keyboard functions as-is, you don't have to do anything at all, and things stay the same. Everybody wins.