Some database hosts have already enabled and require TLS by default, others don't. That creates difficulties when running mysqldump, as it can sometimes fail. I have deployed https://gerrit.wikimedia.org/r/323420 as a temporary workaround, but a proper fix is needed for the client creating the backups to adopt TLS so it doesn't fail AND it is secure.
This is probably something that can be done at the same time that dbstore1001 gets its new disks (T143874).