How do you display the prior work penalty of a tool in minecraft Java

The prior work penalty, is stored in the RepairCost tag of the item and I don't believe it is available in the UI. It can be accessed with a NBT viewer/editor outside of the game. In-game, you can observe it indirectly by placing the item in the anvil and changing the name. The resulting cost will be one more than the "prior work penalty", unless it hits the cap of 39.