Iphone mute slider flipping itself

I have a new iPhone 12 pro. About once a week my ringer stops. When I look at the orange slider switch it is switched to mute. I haven't touched this switch since I got the phone except to turn it back on. I have the Apple silicone case which seems to have plenty of depth to protect the slider. I tried cleaning lint from the switch slot with a brush and air. I have had 6 iPhones, always carry it the same place and never had this problem. What is going on?