Java Edition:Blindness II
Obtaining
Zone dimension
In April Fools version 20w14∞, by warping into the "zones" dimension and standing in the green particles, the player would receive the Blindness II effect, which is unobtainable otherwise. This is a temporary discontinued feature, as the effect only lasts 3 seconds after leaving the particles. Blindness II obtained this way will have the the Ambient tag set to 1 making it produce fewer particles.
Voting for the Blindness II Effect
In the April Fools snapshot 23w13a_or_b, voting for theperma_effectvote rule will give the player a random effect from level 2-6 for an infinite duration. Voting for the drink_air vote rule will allow you to obtain the blindness II effect as a potion for infinite duration by drinking a bottle of void, which is obtained from "drinking" an empty glass bottle.