There are a lot of people who have a reaction to the AirPods material including myself. There are a few rather long threads here on the issue. I have no problem with the older AirPods 1 or 2. AirPods 3 I can use but experience minor irritation. I can not use the Pro's even with third party tips. I get a major irritation that can last for days after very little use.
The inner ear canal has more sensitive skin than the out portion. I believe the newer versions fit deeper into the ear canal (obviously the pros do) than the first gen which irritates the inner part of the ear. You'll find many have posted "fixes" here but it's best to try a different brand that don't cause irritation. I have gone back to using Gen 2 occasionally for phone calls and over ear headphones.