Manual intervention for pacman 7.0.0 and local repositories required
With the release of version 7.0.0 pacman has added support for downloading packages as a separate user with dropped privileges.
For users with local repos however this might imply that the download
user does not have access to the files in question, which can be fixed
by assigning the files and folder to the alpm group and ensuring the
executable bit (+x) is set on the folders in question.
$ chown :alpm -R /path/to/local/repo
Remember to merge the .pacnew files to apply the new default.