I'm unsure on an exact start day, as I was waiting for a couple days to see if any updates would fix it, or if the issue would go away on its own.
Within the last week and a half or so my forerunner 165 has been disconnecting/reconnecting when I have one specific app (Palmon Survival if that matters) open. I can open the game and it works fine for about 20 minutes, and then continuously disconnects/reconnects. It will sometime happen outside of the game just by itself as well, but that's sporadic. Once this process starts, it'll continue even outside of the app.
I'm on Android 16 on a Samsung A16 with every new version installed, every app reinstalled (Connect, the game), a repaired watch, a restarted phone, a bluetooth version changed, and pretty much every possible thing that could be done to fix it done short of factory resetting.
After about 10 times of the disconnect/reconnect (which seems to happen instantly) it stays "connected" but no notifications actually go through. When I scroll to the notifications tab it'll say that it's waiting for the phone to connect, quickly flash to the normal screen (no red error), but go back to the error instantly, within half a second.
The Connect app has full permissions, no battery optimization, excluded from deep sleep, deep sleep is disabled, and all that jazz.