Apple Watch Series 6 Burn Marks where the sensor sits

I’ve wore Apple Watches for years now and never had any issues but this week I noticed burn marks on the top of my wrist where the sensor sits. I only wear my watch during the day and never sleep in it. I have the Nike band so it breathes better and less likely to have moisture trapped under the band. I clean my watch 4 times a week after work. I have no marks anywhere the band sits. The burn does not hurt, does not itch, just looks like a small burn. Anybody know what causes this? I see where thousands of other people are having this issue as well but not seeing an answer to what is going on!