AlliedModders - (CS:S) Wrong SteamID-Universe

I have a strange issue with the GetClientAuthId function.
Context: I had a CS:GO server, and since Valve switched to CS2 and CS:GO is more or less dead, I want to migrate this server to CS:S.
Im currently still using my CS:GO database to store things like player profiles and many other things, including the SteamID.
Now, in the database, there's still my "old" SteamID that starts with "STEAM_1:0" from CS:GO.
In the admin.cfg for CS:S, I have accordingly set my id to "STEAM_0:0:".

Now, onto the actual problem:
Although its very rare, sometimes I get a rank again (from my plugin, due to the user profile from the database) and also lose admin rights,
which can be due to the GetClientAuthId function returning the SteamID as "STEAM_1:0" instead of "STEAM_0:0".
Any ideas how this happens?
(Btw, I dont really want to switch to other SteamID formats because it could be a lot of work and might increase the occurrence of bugs in the plugins.)

Thanks