How does Kaspa validate a block found by a solo miner?

Kaspa validates a solo miner's block by checking that the solved puzzle meets the complexity threshold the network itself defined in the original block template. When a miner receives a block template from a node, that template already contains the required difficulty level — set by the whole network, not by the individual miner. If the miner's solution hits that threshold, the finished block is returned to the node and immediately incorporated into the DAG and shared with every other node on the network. For beginners, this is why you cannot submit easier work and claim a reward: the bar is fixed by consensus, and only solutions that clear it are accepted.