Battery draining issue after updating iPhone 12 to iOS 16

I’m facing serious battery draining issue after updating my iPhone 12 to iOS 16. I use Apple Watch Series 7 and after updating my watch to watchOS 9.0 and while using it in the sleep my phone battery declined from 95% to 69% over the night without any screen on time. Is this because of Apple Watch using the iPhone battery extensively for tracking my sleep or is it a bug?

please let me know how to fix this.