Death Health Penalty

• Lose half of your current max HP on death. (e.g. 20->10->5 etc)
• You can regain HP by eating a golden apple, sleeping, or just not dying for half a day.
• Each method gives you 3 hearts, except the enchanted golden apple which fully restores your HP.

If you are looking for 1.20.1 there is Diminishing Health.