Browser closes after start with "Your profile 'MullvadBrowser' could not be loaded". · Issue #46 · flathub/net.mullvad.MullvadBrowser

If you are having issues with Mullvad in Linux (Flatpak) and getting a message along the lines of ""Your profile 'MullvadBrowser' could not be loaded"", it's a known bug and the only workaround right now is to use the test version:

flatpak install --user https://dl.flathub.org/build-repo/112221/net.mullvad.MullvadBrowser.flatpakref