The handy part about Firefox, unlike Chrome, will shrink tabs to a minimum width and then make them a horizontally scrolling list. I am somewhat of a tab hoarder (I also keep browser windows on vertical monitors), so using Chrome, where it would shrink tabs more and more until there's nothing but a sliver, wouldn't work. Below are screenshots of examples. Firefox keeps things usable; Chrome not so much. (I also know it isn't 1000 tabs, nor is it close to the amount I keep open on my work laptop).

Firefox: https://yld.moe/raw/nVE.png

Chrome: https://yld.moe/raw/vu8.png

Also, if you're wondering why my tabs look like they're from 2017, that's just another benefit of using Firefox [1]. Although as nice as it being able to actually customize our browsers, it would be nice for Mozilla to stop breaking things for sake of breaking things.

[1]: https://github.com/black7375/Firefox-UI-Fix

That may be a reference to this classic Firefox extension:

https://addons.mozilla.org/en-GB/firefox/addon/tree-style-ta...

My browser looks very similar to this: https://framagit.org/ariasuni/tabcenter-reborn/-/wikis/theme...

Tab list usability remains pretty much the same regardless of how many tabs are open.