invalid or corrupted package (PGP signature)

Problem: On arch-update via pacman the following error occurs: Error: rubberband: signature from “David Runge ” is marginal trust :: File /var/cache/pacman/pkg/rubberband-3.0.0-2-x86_64.pkg.tar.zst is corrupted (invalid or corrupted package (PGP signature)). Do you want to delete it? [Y/n] n error: failed to commit transaction (invalid or corrupted package) Errors occurred, no packages were upgraded. -> error installing repo packages Steps taken:...