Mob Kabob advancement does not grant experience upon completion

The Bug:

The "Mob Kabob" advancement doesn’t grant experience upon completion.

All challenge advancements grant experience upon completion, but the "Mob Kabob" advancement doesn’t. Relates to MC-249782.

Steps to Reproduce:

1. Switch to survival mode and grant yourself the "It Spreads" and "With Our Powers Combined!" advancements by using the commands provided below.

   /advancement grant @s only minecraft:adventure/spear_many_mobs

2. Observe your experience.

3. Take note as to whether or not the "Mob Kabob" advancement doesn’t grant experience upon completion.

Observed Behavior:

Experience isn't granted upon completion of the advancement.

Expected Behavior:

Experience would be granted upon completion of the advancement.