I connected to another OneDrive within the same Office365 family subscription and was able to back up properly for a few days. Then, I decided to switch back to the original subscription, deleting old backups and folders first. Unfortunately, while the connection was successful and folders were created, the backup did not work.
So, I went back to the OneDrive that was working, but that one has very limited space left.
Here’s a tip: Consider taking a free 1-month trial subscription of Acronis. Be sure to avoid the trial via Plesk, as it seems limited to 100GB. Instead, take the trial directly from Acronis. Afterward, create a user, install the extension in Plesk, and use that user. This way, you'll get unlimited backup space for a month.
Now, you just have to wait and hope this gets solved before the trial is over.