How Does the “Orphan Block” Mechanism Discourage Fee Sniping?

An orphan block (or stale block) is a valid block that is not included in the main blockchain because another block at the same height was found and propagated faster, becoming the "winner" under the longest chain rule. Miners who build on the orphan block lose their block reward and fees.

This mechanism discourages fee sniping because the risk of their block becoming an orphan (and losing all rewards) outweighs the potential gain of stealing fees.