Apple Watch SE2 Battery Not Holding Charge

I have a 2 year old Apple Watch SE. In the past few months it is intermittently (more often than not) unable to last a day on a full charge. The watch sometimes just sits on my desk and loses 10% an hour. I have re-paired my watch and phone multiple times during this time period. It fixes it for a few days and then it's back to not staying charged. The Battery Health is at 86%, so I don't think Apple will replace the battery even if I pay. I also don't think there is really anything wrong with the battery since there are days when it does stay charged. I have made sure that there are no apps working in the background. I am running iOS 18.1.1 on my phone and watchOS 11.1(22R585). I'm at a loss what to do. A 2 year old watch should not be running out of power after only 13 hours.