June 2021
Firefox 89 changed right-click functionality on macOS. Previously, in a right click menu, typing a letter triggered an option in the menu. For example, rightclicking on a link and pressing t would open the link in a new tab.
But with the June 1 release, that is no longer the case. Now, pressing a letter highlights a menu item, but does not trigger it. It even highlights a different menu item from before. It is a side effect of using the native context menus on macOS.
Native context menus: Context menus on macOS are now native and support Dark Mode.
We can fix this by changing the about:config setting widget.macos.native-context-menus to true. Then Firefox uses its own context menus, so typing a letter triggers the menu item, as in previous browser versions.
Interestingly, this change was landed for a bug reported a long time ago in the year 2000.