XS Max battery drain in standby

I purchased an iPhone XS Max 64gb a few weeks ago, and the battery life was not good from the start.

The battery drains between 4-5% per hour in standby. This is with background app refresh, location services, screen time and raise to wake turned off. The battery info in settings hasn’t helped either, both screen on and off times are low, but the battery drain persists.

As a last resort, I did a clean install through iTunes with the phone in DFU mode. This made no difference!

Any advice would be greatly appreciated!