Are you saying that shortcut should work on those 3 browsers and doesn't or that it doesn't work on Firefox only? It should work on Firefox. I hope these articles help. A new profile is a quick way of testing whether it's the profile or something else. Make sure the shortcut isn't being used by Windows 11.

https://support.mozilla.org/en-US/kb/keyboard-shortcuts-perform-firefox-tasks-quickly https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems (also deals with hardware acceleration) https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

No sorry guys, none of that has done anything. Can't find anything that says the shortcut is being used by Windows either. Shortcut works on no browsers

Can you open the Library via "Manage Bookmarks" in the Bookmarks menu (menu bar or "3-bar" Firefox menu button drop-down list) ? Does it show the "Ctrl+Shift+O" (letter 'O') next to "Manage Bookmarks" in one of those menus ?