Minecraft wiki entry for Development_versions, associated text: Chance of setting the target on fire when burning, and the duration of the effect, now depends on raw regional difficulty.
Chance is now (30 × RegionalDifficulty)%; formerly 30% on Easy, 60% on Normal, 90% on Hard.
Duration is now 2 × floor(RegionalDifficulty) seconds; formerly 2 seconds on Easy, 4 on Normal, 6 on Hard.
Husk hunger effect duration now depends on raw regional difficulty.
Duration is now 7 × floor(RegionalDifficulty) seconds; formerly 7 seconds on Easy, 14 on Normal, 21 on Hard.