Can a Miner Submit a “Stale Share” and What Is the Consequence?

Yes, a miner can submit a "stale share." A stale share is a valid proof-of-work based on a block template that is no longer the current, active template because another pool or miner has already found the next block. The consequence is that the stale share is rejected by the pool and does not count towards the miner's payout.

Stale shares are usually caused by high latency or slow network connectivity.