If the miners are the ones who validate the transactions in order to obtain the rewards from the network,
miners do not "validate" transactions. the only thing that miners do is performing hashes to find a good one below a certain target as part of the proof of work algorithm.
Miners don't validate transactions? Don't miners create blocks and don't they validate those transactions that go into their blocks?
no they do not.
a miner is only concerned about the block header and the target. so basically they only receive and handle 80 bytes and then repeatedly hash that to find the result.
as i said a "node" validates transactions, builds merkle root, builds the block, builds that block's header and sends that header to the miner to hash. the miner doesn't even have to look at that header to see if it is valid or not!
a miner can run a node to validate himself but that still is his
node that is doing the validation. and nowadays that miners connect to pools so they don't even have to run a node, they fully trust the pool to do everything and only sends them a correct header to hash.
miners also are nodes but nodes not necessarily are miners
actually a miner is someone with computing power aka someone who has the equipment (CPU, GPU, ASIC,...) and nothing more.