https://www.reddit.com/r/Jeep/comments/194cbbj/turn_offdisconnect_remote_access_to_my_2021_gcth/

I just got a text from my dealership saying my oil light was on. Super pissed off about it... When I got the Jeep 2 years ago I asked Jeep to turn off ALL remote access/phone home capabilities to the vehicle. I was on the phone for a couple hours with them until I finally got someone who said they did it.

Weather alerts, contextual ads on my console, distant recording of my travels, whatever, I wanted everything off.

It has a 4G cellular module in the head unit, which connects to a separate 4G antenna via a port on the back of the head unit. Unplug the antenna from the head unit and it cannot communicate to anything. Obviously you have to remove a bunch of trim and the unit.

Now, it's possible that during maintenance, the process might involve uploading or downloading data to/from the manufacturer. That's hard to avoid.