I bought my Powerbeats Pros (PBPs) in June 2019 and used them intermittently for a few months and don't remember any problems, but later on when I started to use them more regularly and for longer periods I noticed the maddeningly itchy ears, the clear liquid discharge and the peeling skin. It got really bad and eventually I couldn't use them any more. I tried a test whereby I waited a couple of weeks until my ears cleared up, had my skin checked as normal by my doctor, put the PBPs in for 4 hours (they itched like crazy after 2 hours), and then had my doctor look at my ears right afterwards, and she confirmed contact dermatitis from wearing the PBPs.
I contacted Apple, described the problem, sent photos like these...
... sent doctors' reports about contact dermatitis after wearing them, etc. but all to no avail.
Too bad, because other than those problems they are certainly the best in-ear 'phones I have ever had, and besides the great sound quality, I especially like the ear hooks because my ear shape just doesn't hold onto any of the other in-ear 'phones I have tried over the years. I thought I had finally found the earphones I've been looking for for years! But no...
My theory is that Apple used a nano-coating to sweatproof the PBPs and that's what is causing the terrible skin reaction. I would be really pleased if a) Apple would acknowledge and seriously address this problem, and b) produce new PBPs without the sweatproof nano-coating to see if that solves the problem. The design is great, but the execution of the design is badly flawed and in my estimation, the fact that the company seems not to be interested in dealing with the problem hurts Apple's reputation. Surely the world's richest corporation should be willing to go the extra mile to help loyal customers like me (since 1991!)
By the way, there's a long but now-archived discussion about this problem on Reddit: https://www.reddit.com/r/powerbeatspro/comments/d1m3w3/allergic_to_powerbeats_pro/?sort=new