Acronis Backup Cloud: after disabling all but TLSv1.2 protocols SQL application-aware backup fails with warning "Failed to collect the metadata of the SQL Server databases selected for backup."

After you have disabled SSL 3.0, TLS 1.0, TLS 1.1 and left only TLS 1.2 running on the machine, application-aware backup of an SQL server finishes with a warning:

Error code: 4358
Module: 87
LineInfo: 0xEC865955C73BB27A
Fields: {"$module":"aavb_mssql_backuper_vsa64_11010"}
Message: Failed to collect the metadata of the SQL Server databases selected for backup. The databases will not be backed up.

If you try to edit of specify credentials for an SQL server user, you get these errors:

Cannot collect the metadata of Microsoft SQL Server
The specified user is not a member of the sysadmin role in SQL Server instance 'Instance_name'.
Cannot collect the metadata of Microsoft SQL Server
Cannot back up the SQL Server instances due to environment issues.