LibreWolf has an official Flatpak, which is great for Linux users. The Mullvad Browser Flatpak is not official and allegedly makes suspicious connections.

LibreWolf has good private default settings, but the Mullvad Browser and Tor Browser can go the extra mile because they’re meant to blend into a crowd, through VPN traffic and the Tor Network respectively. If you plan to log-in to sites, install extensions, enable uBlock Origin lists, or customize your browser at all, you defeat the purpose of those browsers.

LibreWolf by comparison is far more reasonable to customize. They even have a custom settings page for the more intense privacy settings among other things. Enabling persistent storage for sites you log into is easier because it’s not forced into Private Browsing all the time. These changes are reasonable because the goal is not to blend into a specific crowd.

There’s no reason you can’t use all these browsers (and more) if their use cases sound relevant to you. I use LibreWolf, Mullvad, Tor, Brave, Vanadium, Mull, and even Edge depending on my needs.