My recently-purchased Pro 3s have some oddities when using transparency mode. It seems they sometimes apply a noise-cancellation effect. I can hear the difference and feel the pressure, and after a bit things return to normal. What I find especially odd is that this rarely happens with both AirPods at once. Usually only one AirPod at a time is doing this.
I also discovered that I can get some amount of this effect consistently by whistling. I can hear a reduction in background noise, and the effect persists a bit after I stop. Maybe high-pitched sounds are the cause.
Is this typical behavior for the Pro 3s? I upgraded from my AirPod 4s with ANC which has, in my opinion, superior transparency mode. At first I was willing to accept the reduction in transparency mode quality, but this is too bizarre for me to ignore.