USB tethering without consuming mobile data

I’m using a mobile data and uses it to provide internet to my PC via USB tethering. I’m also using AudioRelay via USB tethering and this consumes a significant amount of my data relative to my other activities (e.g. gaming). My problem is how to continue these two functions without AudioRelay consuming a mobile data?
I already tried blocking AudioRelay from accessing the internet and it seems to be not the solution.

Android 11, OPPO A5 2020, AudioRelay 0.26.1
Windows 11, Acer, AudioRelay 0.27.5