Undead vs Healing Magic?

I could have sworn they said in some earlier video that there could be interactions between undead and healing magic in the 2024 rules. Today's New Undead video didn't seem to allude to anything like that.

I thought some undead would have something like:
Rejuvenation Aversion. If this creature would regain hit points as a result of a leveled spell, it instead takes the same amount as radiant damage.

Did I misunderstand something?