Yes, miners need to know about unconfirmed transactions, but they do so via nodes. Usually what happens is that mining pools run several nodes, and then create candidate blocks which are sent to individual miners. The individual miners themselves don't need to keep their own mempool or run their own node, because the mining pool gathers the necessary data for them via its nodes.
In here youre taking about miners which are a part of a mining pool?
Cause if so, then okey, I didnt actually look through technical part of these mining pools.
But what about a client who launched his own Bitcoin Core client? Does he have a mempool? Cause as far as I know yes, he does. But maybe Im mistaken