I also have a 2022 MX LR, and had this issue for a year now, had taken the car back to Tesla for balancing repeatedly (5 or 6 times) and also took the car to an independent shop for balancing once. It never got fixed, just varying degrees of vibration, usually starting around 78 mph and getting worse until 86 mph, then going away at higher speed.
Well, I finally fixed it! One of the veteran service people at my local SC told me that the stock Continental tires are "mid range" and that I might want to consider going to Discount Tire, which is now a Tesla authorized partner, amd putting premium tires on. I had only driven 15k miles on my Continental tires, but I went ahead and took advantage of am instant rebate + a mail in rebate from Pirelli, and replaced all 4 tires.
So far, it has been an immediate massive improvement and the tires also seem to feel better on the road. Maybe my imagination but I doubt it. All in cost was about $1,200, and this includes lifetime balance and rotate, + a 50k mile warranty.
Wanted to post this here as my ability to now use Autopilot at 80-85 is back, before it had been too annoying bc of the vibration.
I chose the Pirellis over the Michelins as the tech at Discount Tire said the Michelins aren't as smooth on the road.
Good luck and let me know if you have any questions!