Iphone goes into silent mode without touching silent button

IPHONE PUTS ITSELF INTO SILENT MODE WITHOUT TOUCHING THE BUTTON!!!

Apple has told me multiple times this is a phone issue. It started with my XR, I have had 2 XRs, both new and both did it. I received a 14 Pro Max 1t as a retirement gift days after they were released and this phone ALSO puts itself into silent mode. The only consistency across the phones is that I have an apple watch. However, I have had 3 or 4 different apple watches and the one connected now is an ultra. This is also happens on other iphones- I am not the only one. This is not a result of headphones or any other bluetooth item synced to it. I have always kept them updated. I actually accidentally got a video of it a year or so ago- sent it to apple with no resolution. Every update it gets a little less often but it is still happening regularly (several times a week). I was working in the field with apple employees who also saw it happen and were stumped- stated phone needed to be returned and checked out thoroughly (it was about 5 weeks old). This is NOT a result of the button being pushed- the button is NOT pushed and it goes into silent. The only fix is to wait until I miss calls or texts turn it into silent mode and then click it back out. This happens when I am asleep routinely whether or not it is charging. Someone needs to address this- and maybe then you can replace this pos ultra watch- Your products are becoming substantially more expensive with less thought and care to honoring your warranties or fixing your software issues. Do better