Sculk catalysts don't spread sculk when the player kills the ender dragon, which is inconsistent with other mobs that drop xp. The wither on the other hand even though it's also considered a boss, does spread sculk (although not reliably due to MC-249259).

Expected behavior
A sculk catalyst near an ender dragon would spread sculk according to it's xp reward after being killed.

Observed behavior
The sculk catalyst blooms, but doesn't spread sculk.

How to reproduce

1. Ensure mob griefing is disabled.
2. Place a catalyst with other blocks around that can spread into sculk.
3. Set your damage to a high value enough to kill the dragon with one hit (/attribute).
4. Summon the ender dragon near the catalyst and kill it.
5. Notice how the dragon drops xp and the catalyst doesn't spread sculk.