I don't take it too seriously. I have come across such cases several times. Where the buyer marks the order as paid without paying and sends a notice to confirm the order. In such a situation, if he asks to confirm the order without sending the money, then at the initial stage you send him a message that you did not receive the money. If he does not respond to that message, then you can take help from the exchange support or report him on his profile. This is part of the basic knowledge for a P2P user.
I do not think this is a special scam or warning. Even if the buyer cannot show any proof of payment, I think the exchange authorities will not evaluate his report and will not send crypto to the scammer without your consent. Because, the exchange authorities do not take any action on the report of one party unless you ignore them.
I think you should start taking it seriously, I believe you should start taking anything that has to do with your finances seriously, yes it may seem little or unnecessary because you fill so but at any time it could hurt you.
It won't cost you anything to talk to the buyer about an order that is marked paid when in reality it isn't.
I have been using exchange for a long time myself and one thing that has kept me safe is doing the right thing even if some of them are trivial and unnecessary.