If I sell some btc with paypal. The transaction occurs and I get the paypal in my account. Then I use the paypal instantly. Will the buyer be able to reverse the transaction once the paypal has been used form my account?
Usually, exchange btc for paypal can be made with trusted sellers within trusted platforms or in decentralized exchanges with enforcement of KYC verification.
The refund option with paypal is a real issue for those who are willing to buy cryptocurrencies in general and in a P2P way in particular.