Because of Bug 1680757 - Thunderbird 78.5.1: Importing OpenPGP keys from file is broken on macOS we have set update rules for Macs to NOT update to 78.5.1 - Macs will still update to 78.5.0. This was the simplest and quickest way to deal with the regression from Bug 1665145 - Importing OpenPGP public keys: Allow multi-file selection.