When I started to challenge the trial chamber, I suddenly found something was wrong, all trial spawners with skeleton type mobs has unusually long delays between spawn in chamber_8.

After repeated testing, I can confirm that this issue affects all skeleton variants spawned in chamber_8, including skeletons, strays and boggeds.

Seed: 2949666280069919304

Coordinate: 1819 2 1849, 5265 2 40