All transactions above some amount trigger 0 dollar transactions within few minutes. It's a massive attack that has been going for some time. Just look at the block chain. Even if it happens one in a million transaction, it's still profitable and scammer makes money.
Perhaps a message to avoid the shitty centralized blockchains that are easy to spam and stick to the real OGs
But also people ought to be extra careful and responsible for their funds. You can't claim to advocate for cryptos, being your own bank and then end up losing money in this fashion is scammers.