Hi Nicole!
Thanks for coming over to the forum for us! We did manage to set this up and test Total Upkeep with WordPress 6.4.3 and PHP 8.2 and did not find any issues or warnings. You can try completely removing Total Upkeep and then reinstalling it on your WordPress site to see if it clears up your warnings.
You also want to attempt to run a backup to make sure the backup process is functioning properly. If the backup does fail you should be able to get some information from viewing the backup logs in your Total Upkeep keep dashboard. Navigate to Total Upkeep > Tools > Logs and look for your most recent log with a name like archive-XXXXXXXX.log.
If you can copy that and use PasteBin to create a link and paste it here, we’ll be able to get some more information about what went wrong.
Note that even your initial message was only a warning and not an actual error so please let us know right away if you have trouble with backups.
Thanks Nicole, I really hope this helps!