Somebody sells at 4k instead of 40k. Who gets it?

AFAIK, if it is the same as stocks, then it is "The person who entered it first", meaning:

If somebody put in the limit order to Buy At $33,000, before you, then your $4000 will be matched to his limit order, but because he entered it first, then the transaction between you and him will be $30,000. That's the rule.

There are tons of buy order to buy at $33,000 or $32,000, so the $4000 will be matched by those numbers first.