I see that blacklist was added for dreadful dirt but how does one do it since no configs can be found

Using entity type tags in a datapack, these are the tags available in 1.19+
https://github.com/vadis365/Mob-Grinding-Utils/tree/MC1.19/MobGrindingUtils/MobGrindingUtils/src/generated/resources/data/mob_grinding_utils/tags/entity_types