Looks like PHPmailer doesn't fully support PHP 8 yet. Bummer.Cheers,Franco
You did the right thing.PHP 8 has had some things changed and not all third party software seems to be ready.Cheers,Franco
EDIT SOLVED: I simply uninstalled PHPmailer from the command line and it also uninstalled os-mail-backup. Now the Cron starts with no errors.