fyber and other offerwalls

Does fyber and other offer walls pay the app owners even if there app users use vpns??

If the volume of VPS usage will be high then most likely your account will get suspended. You should avoid and ban the users who use VPN because in the end it’s you who will get into troubles. Had some issues in the past with Fyber network regarding this, but it got resolved, however it took much time and some legal factors involved as well.