Secure BackupData on Internet-Server

I have found a topic from 2018 about encryt backuped data on server location. But no solution to this.
Can somebody tell me, if this is possible?

Kind regards

You can turn on BitLocker for the storage, or some other disk encryption method, doesn’t do much that’s particularly helpful, since the server typically runs 24/7 with the encrypted storage unlocked. You’d be protected against someone unplugging the drive & running off with it then getting the data though.

We want to backup several customers servers on one single cloud server and monitor them all together. To get conform with the german dsgvo, you have to encrypt the stored data with a password which has been set by the customer it self. It would by nice to store each client in a different 7zip-archive, secured by the internet- or customer password. Would it be difficult to implement this feature? Or is it possible to set this encryption in an after-backup-script and an decryption in an before-backup-script?