When you break the nether sprout block an invisible block will drop, can only be located by its shadow. If you pick it up you wont be able to drop it by pressing "q", ony if you push it out of the inventory. You can't attack an entity. If you break the ground it'll disappear and you'll be able do jump down, after you're submerged in 2 or more blocks you'll start to suffocate in ghost blocks. It's texture resembles a spawn egg, but filling the entire square. Two things to note is if a sizeable quantiy (about 35 of the thing) is dropped and you try to break more nether sprout blocks nothing will drop. Another thing is that if you break a block with the glitched nether sprout block nothing will drop and the break sound won't ever happen. Entities cannot be damaged by it and the glitched nether sprout is completly invisible when rendered in your hand and in the world, only in your inventory. Unsure if it affects any snapshots in java nor the beta 1.16.0.63 bedrock edition.