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A "mass payment" pp transaction is going to be reversible because the owner of the sending account can claim their account was hacked and/or the funds could originate via fraudulent means.
And if PayPal doesn't reverse it after receiving those types of claims, a court will order PayPal to reverse it, after receiving sufficient evidence. The BTC sender loses the fiat they were sent in exchange, as it's reversed back to the original PayPal accountholder, the anonymous BTC receiving scammer gets away scot-free.
If the court knows who received the BTC. Non-dumbest PayPal scammers wouldn't use accounts with their own identity tied to them in any way.