How Does the Concept of “Economic Finality” Relate to the Security of a Blockchain against Double-Spending?

Economic finality refers to the point where the cost of reversing a transaction or block is so prohibitively high that it becomes economically irrational to attempt. For PoW chains, this cost is tied to the amount of energy and hardware required to generate a longer chain and overcome the current one.

The deeper a transaction is buried under subsequent blocks, the higher the economic finality. A high degree of economic finality is a direct measure of a blockchain's security against double-spending, as it assures users that their transactions are irreversible.