iphone audio thru bluetooth goes up and down

I am running the latest OS on a new iPhone 13pro but any audio such as music, podcasts, Spotify, audible the audio goes up and down in volume when playing. I noticed this when I upgraded my OS to 15 on my iPhone 10 thought it was something wrong with the phone so I upgraded to the 13pro and notice it continues with anything thru bluetooth such as my CarPlay on a Pioneer stereo, my iPod pros or 3M Worktunes. Its very frustrating. I have looked thru all my audio settings and I dont see anything that would cause the audio volume to go down and there is no pattern to when it happens as sometimes its only a second or two and others its for a longer duration. I believe this is a bug in the bluetooth on the last couple OS upgrades.