Support

I do not see any such problem with quota management. Moreover, we have not touched the quotas code since version 6. Without further information I will have to give you some more generic advice.

Please make sure that you have enabled the Enable Remote Quotas. Otherwise it's just local quotas (on the web server) which do nothing when you are automatically transferring your files to OneDrive and have them removed from your web servers. Please double check, don't just rely on your being sure you did so.

Likewise, please double check that the backup profile really has set up count quotas for 5 files and no other quotas than that. More specifically, if you have enabled the maximum backup age quotas all other quota settings are ignored.

Please remember that quotas are applied per backup profile. If you have multiple backup profiles each one has its own quotas. So if you have two backup profiles and both have a quota limit of 5 archive files you will see up to 10 archive sets (2 profiles x 5 archive sets / profile) in OneDrive.

Quotas are calculated by reading the database entries for backup attempts, NOT the files on your OneDrive drive. This is INTENTIONAL. It prevents accidentally deleting files from your drive you didn't mean to delete, including files not belonging to this backup profile, this site or even Akeeba Backup at all.

This also means that if you delete backup archives from OneDrive outside of Akeeba Backup, if you delete backup records from Akeeba Backup (e.g. with the obsolete records quota) or restore your site from a backup (which may be effectively the  same as deleting backup records) the calculation of remote quotas will be wrong compared to the actual state of the files stored in OneDrive and you may have to delete files manually.

Remote quotas are applied towards the very end of the backup process, after the files have been transferred to OneDrive. If the transfer fails for any reason the quotas will not be applied and your backup record will have a status of OK (checkmark on green background) instead of Remote (cloud on blue background). Please check that.

Finally, please do check that you can delete files in OneDrive through Akeeba Backup. Find a backup record which has the Remote status and whose files you can see in OneDrive. Click on Manage Remote Stored Files and click on the button to delete the remotely stored files. Check that the files are gone in OneDrive. If this doesn't work or you get an error then your OneDrive settings do not allow deleting files through Akeeba Backup.

If this does not help I need you to ZIP and attach the backup log files from the last successive 6 backups taken with the backup profile where you have enabled the remote quotas. Moreover, I will need you to manually verify that the files from all of these backups really do exist in the OneDrive directory you have configured in Akeeba Backup.