I personally got a new phone (15 Pro Max), and it's been better (i.e. forgot to charge the other night, and battery went from 82% > 79% in 5 hours).Any updates, did you try any of the suggestions and came any closer to a solution.
I feel like iOS 17.2 or 17.3 has improved this.
(note that every time this DOES occur - and it has come back - I delete and reinstall the native Apple Mail app)