Signatures don't validate, I guess I'll pass for now.
$ gpg --verify mullvad-browser-linux64-12.0.4_ALL.tar.xz.asc
gpg: assuming signed data in 'mullvad-browser-linux64-12.0.4_ALL.tar.xz'
gpg: Signature made Fri 31 Mar 2023 01:15:54 AM CST
gpg: using RSA key E53D989A9E2D47BF
gpg: Can't check signature: No public key
$ gpg --verify mullvad-browser-linux64-12.0.4_ALL.tar.xz.asc gpg: assuming signed data in 'mullvad-browser-linux64-12.0.4_ALL.tar.xz' gpg: Signature made Fri 31 Mar 2023 01:15:54 AM CST gpg: using RSA key E53D989A9E2D47BF gpg: Can't check signature: No public key