In the 1.9 version of Dynamic Difficulty 4 new difficulty types have been added, these are per-biome, time, region and per world. Tons of bugs have been squashed. Creeperdamage prevention has been added, max health and cancel health regen work again.
Sadly due to how the code has changed, DynamicDifficulty 1.9 only supports Minecraft 1.21.4 and up.