What you want is ridiculous and counter-productive, and you should feel bad for even desiring such nonsense.
Having said that - this appears to suggest you’re not alone in your self-harming endeavours and proposes editing userChrome.css to achieve it. Technically it is setting a min width to a tab, but <1px would be impossible to display and click on anyway.
I genuinely think the web has become horrible enough where the browser you use does not really matter from the technical perspective.
It does, however, incredibly important to have more than 1 engine competing, as currently Firefox is the only mainstream browser not built on chromium/google.
fedia login error on some threads (fedia.io) en
when loading these pages:...
Recent things google, really want to use firefox now, but... (fedia.io) en
So, with google being who they are wanting to create a more and more hostile environment using chrome is increasingly becoming more meh....
Firefox 115 released (mozilla.org)