My first and only maintenance so far on my 2021 850 was just earlier this week. It was at 19 hours and 164 miles.
I replaced engine oil and filter, as well as front and rear diff fluid, and trans fluid. I also used my new Havok Industries wheel bearing greaser at all four corners. Greased all grease zerks too.
Air filter still looked like new, but I did put a nice coat of grease around the rubber boot and sealing surface to prevent ever sucking dust around there.
I'm not a fan of how the air filter is held in place on these. If that little rubber strap fails, the door could come open or fall off, and allow the filter to come loose. Then again, maybe the seat fits right up against that door too, I can't remember now. Maybe the seat would hold it in place if the rubber strap failed? I'll have to look at it in the morning.