apple watch series 10 intermittently discharging in a few hours

I bought a Series 10 apple watch about a month ago, and every once in a while (1 day a week on average), the watch goes from 100% charge to 5% in a matter of 3-4 hours for no apparent reason. Some days the charge lasts 30 hours. Some days only 3-4. I am baffled. I am not actively running a heart monitor or any other app in the background that I am aware of. Any suggestions on how to fix on my own would be greatly appreciated. If not, I am going to ask that apple replace this watch under warranty. I suspect this is a software glitch, not a hardware glitch since it is intermittent.