subdomain.url.com wrongly redirects to www.subdomain.url.com

I have a subdomain like:
https://sub.url.com
It always redirects to:
https://www.sub.url.com

I can’t figure out the behavior. I checked in the apache directives and saw an
Alias www.sub.url.com
and so I changed it to:
Alias sub.url.com
in both the ssl and regular versions of the file.

I then restarted apache and it still redirects.

(I’m grepping my entire server for ‘www.sub’ right now so will update when that is through.)