When I throw a lingering potion so that it hits an entity from above, it creates the effect "cloud" above the entity. If the entity is a creature/player, it does not get the effect unless it jumps into the cloud. Also, when throwing the potion head-on, the height of the cloud depends on where the creature/player is hit. A hit in the head, for instance, creates a cloud above the ground (but still low enough any creature/player will receive the effect if they walk into the cloud).

To reproduce, simply throw a lingering potion at an entity from above.