It depends on how you play it.
Buying coins and withdrawing funds on the platform itself is not illegal.
But the active way to seek death is to go up and collect a large amount of money and withdraw funds, earning the difference in exchange rates as a large flow, which will be classified as OTC operation crime.
Another way of passively committing a crime is receiving dirty money.
Generally, playing coins on large exchanges is not a big issue, but small exchanges are hard to say, for example, Zhimakaimen. I was previously banned for receiving dirty money, but usually, if this can be explained clearly, it's fine.