The Bug:
"minecraft.custom:minecraft.damage_dealt" doesn't increase when damaging the ender dragon.
Please note that you must attack the ender dragon using a melee source of damage as a result of MC-29519.
Steps to Reproduce:
Create a scoreboard objective for tracking when you deal damage and set it to display on the sidebar by using the commands provided below.
/scoreboard objectives add DamageDealt minecraft.custom:minecraft.damage_dealt
/scoreboard objectives setdisplay sidebar DamageDealt
Summon an ender dragon and attack it.
Take note as to whether or not "minecraft.custom:minecraft.damage_dealt" increases when damaging the ender dragon.
Observed Behavior:
The scoreboard doesn't increase.
Expected Behavior:
The scoreboard would increase.
Can confirm for 1.16.2.