@TechGrips Hi,
Unused XVA means a XVA file is not linked to any metadata (to remove a backup, we first remove the metadata file linked to it, then we remove the XVA), it should be removed by clean vm step. It is not an issue, just an information.
For the second warning "XVA might be broken", this is because the compressed file seems to be corrupted but we cannot be sure. We prefer to warn the user there may be an issue in the file. This should encourage to remake a backup.