Both the comment here and the patch description above still needs to be improved. Perhaps something along these lines.
Checkout v5
Secure boot on Apple Macs with a T2 Security chip cannot read either the EFI variables or the certificates stored in different db's (e.g. db, dbx, MokListXRT). Attempting to read them causes ...
Avoid reading the EFI variables or the certificates stored in different dbs. As a result, without certificates secure boot signature verification fails.
thanks,
Mimi