as i said before: i don't believe it's an FTPS/ TLS 1.3 error. I had these before and these would make a connection impossible, FTPS connects and transfers data so I think the issue is somewhere else.
And it's a proFTPd at my home, not a Strato hidrive
FTPS worked and I just want it to work again.
The problem persists on Plesk Obsidian 18.30 Update 2 on Ubuntu 18.04.5 LTS
Error: Export error: Size of volume backup_2010070007.tar 10736090624 does not match expected one 10736968649. The remote backup may not be restored.
Error: Unable to validate the remote backup. It may not be restored...