OnStar reports location and speed data to the car manufacturer. Sometimes they will sell this data to insurance companies to raise your premium, as several news stores pointed out a few weeks ago. I couldn't really find an advantage to OnStar, (I have my phone to call emergency services) so I disabled it by pulling it's fuse.
For my 2019 bolt, it's f31 in the instrument panel fuse box, just down and to the left of the steering wheel. The fuse box cover comes off when you pull it hard from the bottom.
I was able to find which fuse went to OnStar in the owners manual and labeled on the inside of the fuse box cover. You should be able to find it for your model car there too if it uses OnStar.
I did have the casualty of my speaker for calls and texts. I'm not able to use it right now. I'll see if I can dig in and reconnect it somehow, but we'll see.
Who knows that other into they're snitching back to GM, or what they could do in the future, so I recommend disconnecting it. Good luck!
Cadillac here. I just unscrew the cellular antenna from the onstar module before leaving the lot. Looks like the onstar module is less conveniently located for bolts (it’s under my rear seats, I think it’s behind your screen), but that’s a good way to avoid collateral damage to other things on the same fuse. Since it’s a separate antenna from the gps, I even still get navigation, just without map updates. It’s all the good of a cell jammer, with none of the prison or fines. For now.
Even better because without the antenna load, the transmitter may burn out.