I use Siteground and it has a staging server that AFAIK hasn't been used for at least 6 years ... Nothing at the host has any details of that, archive.org does

I use Siteground and it has a staging server that AFAIK hasn't been used for at least 6 years ... Nothing at the host has any details of that, archive.org doesn't have it in their site URLs, it's not in DNS records, not in .well-known, it was a transient test years ago ... really curious, must be historic data from somewhere?