If you take good pictures of the item you’re selling, pack it well and take pictures of that, and ship with tracking numbers and insurance you can protect yourself against frivolous claims. PayPal is definitely more centered around protecting the buyer, but if you do some simple things that your pretty much need to do anyway nowadays with any internet sale regardless of payment method they can’t just hang you out to dry as a seller with just bullshit.
I’ve unfortunately had to use the claim process with PayPal as a buyer and also have had a buyer try to use it “against me” as a seller. But because I had documentation on my end to refute the claim I was in the clear. If you’re familiar with the claim process you can protect yourself as a seller as well.
In person sales can go bad too, nothing is perfect.