Anecdotal, of course, but I currently have 42 tabs open in Firefox 84 (native M1 build) on an 8gb M1 Mac Mini, as well as two VS Code windows and a bunch of other things like Mail, Calendar, Authy, Bitwarden, etc. As far as memory management is concerned, user experience is indistinguishable from my 32gb Ryzen 3700X desktop with a Samsung NVMe.
8GB is plenty for most people right now. A browser won’t eat that much memory for normal sites and reasonable tab counts.
An interesting thing about the M1’s RAM limit, though, is that it literally can’t get any bigger. 16GB is pushing it, but fitting 32GB into a package-on-package simply can’t be done with our current tech. Apple is solely relying on Moore’s law for future advances because, with the way these processors are designed, external infrastructure would wreck performance.