iPhone XR battery drain issue

Hi All - I've been using iphone XR for the past 4 months and the last 2 months has been such a headache with the battery drain issue on my phone. The battery life was great for the first 2 months but ever since I have upgraded 12.3.1, the battery has been draining very fast even when the phone is on standby without any activity whatsoever. I have waited for iOS 13 thinking that the new OS might fix the battery drain issue but unfortunately the battery drain issue still remain the same even after upgrading to the latest iOS 13.1.2. It drains almost 5% every hour even when the phone is idle during the day as well as overnight whereas earlier it used to be 1-2% when in standby. Tried all the best practices including the last resort of factory reset but the problem remains the same.

I found another user reported the same issue here https://discussions.apple.com/thread/250468933 but could not find any helpful answer to it. Also visited the Apple service center and I was told that the battery is performing normally which I am kind of clueless on what to do now. Any help would be greatly appreciated! Thanks.