You should be on OS9.3
No problems here, and if you spent hours with Apple Support there is not a lot we can add except...
Force restart your watch i.e. press and hold both the side button and Digital Crown for at least 10 seconds, then release both buttons when you see the Apple logo.
Then Force Restart the paired iphone Force restart iPhone – Apple Support (UK)
Then make sure to turn off background app refresh and check walkie talkie is not accidentally turned on.
Try it for a couple of days especially if you sync photos to your Watch.
Then if still no better
Unpair the watch and then pair it again.
Unpair and erase your Apple Watch – Apple Support (UK)
Set up your Apple Watch – Apple Support (UK)
If it still discharges unpair it and pair it again without restoring the backup.
Check that the iPhone is not using any security apps or VPN that can affect apps on the Watch. You don't need any of them and they can be incompatible with iOS16 on the phone.
see also
Apple Watch - Battery - Apple Apple Watch - Battery - Apple (UK)
Batteries - Maximising Performance - Apple Batteries - Maximising Performance - Apple (UK)
You can also check for leaky battery How to check your Apple Watch battery fo… - Apple Community