User Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:75.0) Gecko/20100101 Firefox/75.0
Steps to reproduce:
Updated to Firefox with the new address bar, on my (Fedora Linux) system where Firefox is in a 1080x1920 window (maximized on a portrait-orientation FHD screen).
The autocomplete / suggestion / whatever list that appears when you start typing in the new address bar seems now to only ever render as wide as the address bar itself. Which on a 1080 wide window, with a search box and a few plugins, is only about 573 pixels wide. The margins and the 'fade out' effect on the right hand side of the list effectively eat a little more of that, to the point where you almost never get anywhere close to the full URL or full title of any page in the list. This is particular a problem for trying to sort through many similar URLs, for instance...Bugzilla bugs. See attached screenshot.
It should be possible for this UI element to be much wider, as it was in the previous design. I understand that this doesn't matter a lot if the window is very wide, as is often the case on landscape-oriented screens, but it's a big problem if it isn't.