There's no association with AT&T, Inc. as these were part of the WarnerMedia spin-off.WBD brand of RSN is "AT&T Sportsnet".
I think this is probably a matter of not thinking far enough ahead to do a proper re-brand. HBO Sports actually had a pretty respectable reputation in days gone by but Warner has apparently recognized that HBO doesn't mean much anymore.
I'm guessing that WBD was hoping to sell them off only to find that RSNs are a little toxic (from a business standpoint) nowadays.