Watch uses a LOT of battery
First check for damaged battery...
Charge the watch to 100% at bedtime.
Take it off charge,
Turn it OFF - hold in side button til you see the sliders and tap the tiny off button, top right. Confirm off with slider.
In the morning turn it back on and it should be at least 95%. If NOT then the battery is damaged.
If the battery is OK then unpair the watch and then pair it again.
Test the watch for a day.
Unpair and erase your Apple Watch
Set up your Apple Watch
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
Batteries - Maximising Performance - Apple