I don't know what to suggest, sorry. I've tested with Firefox 84.0.1 just now on our demo site and works fine. The hamburger menus open fine and hovering/clicking on Connections opens the dropdown with with manage/remove connections. Please describe your exact testing process and if you're using a mobile device please provide what device. I've tested Edge, FF, and Chrome as well as Android with Chrome as all working fine.
Below is a screenshot with it expanded fine in Firefox.
In another topic a user has also confirmed is working fine whom originally reported the issue. Please be absolutely sure your install is up to date and if you've any caching to clear it. Demo site has refreshed with a clean install and latest releases as well so you may retry there too.