This bug is directly related to this fix that took place in 1.16.2.0

• The Refreshment enchantment now triggers properly for every mob killed by explosion damage when using Exploding Crossbow or Fireworks Arrow (MCD-7046)

This should've applied for just on-kill enchantments, however it now happens for every enchantment, per every mob within explosion radius, causing enchantments like Unchanting, Critical Hit, Chain Reaction, Committed to trigger for every mob within explosion radius. Unchanting and Critical Hit especially multiplies the explosion damage directly for every mob. Example:

• If an explosive crossbow with Unchanting hits 5 mobs with enchantments, unchanting will trigger 5 times, doubling the explosion damage 5 times for the last mob in the order.
• If an explosive crossbow with chain reaction hits multiple mobs, and chain reaction triggers, chain reaction will trigger for each and every single mob.

Edit: Corpses are confirmed to have an effect aswell. If a corpse is within explosion range, an explosive arrow with the Committed enchantment will deal insta-killing damage.

(check attachment for reference, the screenshots do not belong to me)