IOS 13 volume changes by itself?

Hi, I have an iPhone X with the freshly released iOS 13. Now I notice that the volume sometimes changes slightly even though I do not print a button. So I watch Netflix and it comes without the what presses the volume bar and you see the one to 2 times the volume mostly down regulates.
is this just a buck because the software is so new?

Do not have that

also iPhone X

Do you have a cell phone case? Could be because…

No, it's not on the cell phone case. But thanks 😊

Do not think that's a bug.

Rather another device, like the headphones. Or an Apple Remote nearby.