even with the steam version? i'm not as familiar with their software offerings. i wait until its on gog.
you can make inbound and outbound firewall rules to prevent it from happening. i do this with most software out of principle, and only turn them off if i need to update, or if it prevents operation... at which point i find alternative software
type Firewall into search... then use the wizard for inbound/outbound rule, point it at ootp.exe in the game directory, click finish. repeat for the other direction (in/out).