For such use cases I use different browser profiles. It is a bit tiresome to set up, but afterward it works.

For example, I have a profile for watching videos via Amazon and Netflix, which uses dark mode and some high-resolution extensions, but not tree-style-tabs which I use with my normal browser profile.

For a non-mainstream-feature I thought that rather easy. Open about:profiles, click "create new profile", enter a name, and then use the "Launch profile in new browser" buttons on that page to use that profile.

I have one for work and one for non-work and it's great!

In addition, you might want to add an entry to your system menu or place shortcut somewhere to start a new instance:

  /usr/bin/firefox -P my-profile --no-remote

If you want more fine grained control, check out https://github.com/dyne/tinfoil

I actually have some scripts for managing not just profiles but extensions. Hopefully I can get it cleaned up in time to put on Github.

Profiles are cumbersome in Firefox. Chrome has much better support for Profiles.

Funnily enough, I have extensions disabled in incognito mode, so I use the temporary incognito window for banks and other risky stuff.

As my extensions include ublock0, umatrix and cookie autodelete normal tab close behaviour usually eradicates everything.

This, also as an expansion on this idea, I would love to see per container password management or atleast per Multi-Account container password management.