When I ride with my phone in the middle (back) jersey pocket, it disconnects from the 850 within 5-15 seconds and does not reconnect until I take the phone back out of the pocket. This makes the media controls, tracking, and safety features useless. This has been my experience on every ride with the 850 since I got it, on software versions 7.09 & 7.10.
Oddly, it stays connected just fine in either side jersey pocket, but not as comfortable. I recently moved from the 530 to the 850 and do not recall this issue occurring with the 530. For reference, the phone stays connected to my headphones and watch without issue, and the edge doesn't seem to have issues staying connected to my DI2 or other sensors (occasional power meter drop but reconnects immediately).
I have done the recommended troubleshooting steps of removing the phone from the 850, removing the 850 from the phone / garmin connect app and forgetting the Bluetooth device in Bluetooth settings, then reconnecting everything. This did not change the behavior. Phone is Pixel 10 Pro and no I don't have any metal medical objects in the way.
I have a friend with the 1050 and he hasn't noticed any issues with his phone in the middle jersey pocket.
I wonder if it's an issue with my particular 850 and I should return for a different one (still within 30 days).