I can give you a short-term workaround, but a more durable solution will require more work. '''''Temporary Fix -- for Firefox 89-90 ONLY (not working in Firefox 91)''''' For testing purposes, there is a preference to switch between new style and old style menus. It helps with the spacing, but might be a tad bit glitchy: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. (2) In the search box in the page, type or paste '''browser.proton.contextmenus.enabled''' and pause while the list is filtered (3) Double-click the preference to switch between '''true''' (new style) and '''false''' (old style) ''In my test, the Bookmarks menu on the optional top Menu Bar was messed up in the existing window, but looked okay in a new window.'' '''''Longer Term Community Workaround''''' This involves setting up a userChrome.css file. This full instructions are in the following thread: https://support.mozilla.org/questions/1337841 I'm sure we'll refine that during the course of the month so when the temporary preference is removed, it will be airtight.