AirPods Pro: clogged ears (Airplane Ear or Eardrum Suck effect) with noise cancellation turned on

The effect you are describing is commonly referred to as "eardrum suck". It's a common complaint for any type of noise-cancelling earphones.

Only some people are sensitive to it, and the stronger the noise-cancellation, the more likely it will bother you. Headphones seem more likely to cause it than earbuds.

According to Brent Butterworth, a headphone reviewer, it's an aural illusion caused by the nature of noise cancelling circuitry (there is no pressure on your eardrum, it just feels that way). It's a little difficult to explain succinctly, but this article goes into all the details: https://www.soundstagesolo.com/index.php/features/178-eardrum-suck-the-mystery-solved