Mullvad Browser and LibreWolf have two completely different strategies to avoid fingerprinting. Mullvad Browser operates on everyone having the same configuration to blend in - if you want to use it, you need to avoid changing any of the settings. LibreWolf, on the other hand, works by spoofing a different fingerprint every session. It will look unique to Cover Your Tracks and the like, but it will be different every time you close and reopen it. Again, it works best if you don't mess with the settings.

I believe both Mullvad Browser and LibreWolf come with uBlockOrigin pre-installed. Just about anything you want to do regarding blocking ads or scripts can be done in UBO's settings; do NOT add extra "privacy" add-ons as you will only make yourself easier to fingerprint.

If you're looking for something to use with actual accounts (like banking), use hardened Firefox (with arkenfox) or a hardened chromium browser. Neither Mullvad Browser nor LibreWolf (and especially NOT Tor) are designed for that use case.

As an aside, you can use multiple browsers for different use cases. I honestly think that's best practices at this point, but you'd have to be good about not overlapping your browsing on them (i.e., not visiting/logging into the same website on multiple browsers).