murdocklawless yes, if you have any extension installed that needs PHP 8.0, then you'll have to run everything Flarum with 8.0, even if the specific action doesn't seem to involve that particular extension. The webserver, PHP commands and Composer commands must all run with the same PHP version. This includes the CRON job entry as well!
On most hostings, you can change the default PHP version for the command line if you have multiple installed. Look for the setting if you have a managed hosting web UI, or on many Linux distributions check out the "update alternatives" utility. If you don't use the older PHP versions for anything else, you might also be able to uninstall them completely.
