Setup Single Player, no mods, Original Official client.
Wither Rose Farm design by raysworks, step by step build showcased by shulkercraft video here:-
https://www.youtube.com/watch?v=wfr0s1CnC4I&t=417s
world download available on the YT vid.

Screenshot is from the world download.

Endermen drop 42 blocks and survive, and pre 1.19.3, the blast from the wither would finish them off, producing wither roses. Its a great farm.

In 1.19.3, the blast from the wither no longer damages endermen

Test 1: place a block in trajectory of missile.. place a chicken.. Wither missile kills it and produces a wither rose.. as expected
test 2: use a spawn egg to place an endermen on the same block, the blast from the missile does not damage the endermen!
test 3: other hostile mobs, tried with a zombie, zombie takes damage

The Raysworks design uses uses an endermen farm to drop them 42 blocks, next to the bedrock blocks of the end gateway, with a wither trapped in it. Normally (<1.19.3) the blast from the wither would kill them off.
Now it does no damage at all, and you end up with lots of endermen entity cramming instead.

Difficulty is set to hard mode, standard world defaults, no gamerules changed.
(not test