Personal fan favorite:
Same. Librewolf and Mullvad browsers FTW. Librewolf comes with Ublock Origin and turns off a lot of privacy invasive configuration flags by default.
Combine this with awesome extensions like NoScript (ublock can also block JS, but I like NoScript’s interface better), and Chameleon (spoof your user agent string) and you’re good. Add on LibRedirect to redirect you to alternative front ends like Invidious, Libreddit, Nitter, Scribe, and also paste in a Bypass Paywalls script into Ublock’s filter list, and yeah…there’s a LOT of options to give the middle finger to advertisers, I mean, just look into using yt-dlp with YouTube sponsor block, and you can go far with this.
I wouldn’t use any other extensions, especially something like Chamaleon for Mullvad browser though.
Extensions, specifically the ones that change how a website behaves or how a website sees the user (such as an adblocker or a user agent string switcher) can be detected. Mullvad only comes with NoScript and uBlock Origin which is enough most of the time, and installing other extensions can be used to fingerprint you, especially since Mullvad tries to have every user seem like the same user to websites (which is why things such as letterboxing are enabled).