How long have you had your R1T, and when did the noise start?
I've been having the same problem. I just picked up my R1T and noticed the wind noise right away. It seems to be coming from the top of the A-pillar. I'm wondering if it's a trim piece issue that needs to be replaced. I took my truck in for service a few weeks ago, and they just said it was normal.
It's starting to feel like Rivian is just trying to see what they can get away with. A lot of people have been complaining about wind noise, the tonneau cover, the front end thunk, the unreliable phone key, and missing all-weather floor mats. It's like they're just ignoring these issues.
I actually found a temporary fix for the wind noise by putting tape over the gap between the A-pillar and the windshield. I'm going to take my truck back in for service again and see if they can fix it properly this time.