Minecraft wiki entry for Caves_%26_Cliffs, associated text: Similar to snow, but entities fall through it. The fall is similar to the effect of cobwebs, but faster.
If the player does not have any leather armor equipped and they walk or fall in, they start to freeze and take damage.
Freezing lowers the player's FOV (field of view), turns the health bar blue, and puts a frosty vignette on their screen.
Any leather armor prevents freezing.
Wearing leather boots allows the player to walk on top of powder snow and make it function like scaffolding.
Most mobs can also take freezing damage. Polar bears, strays, and snow golems are immune to freezing.
Certain mobs have unique properties with powder snow.
Skeletons convert into strays after staying inside of powder snow for too long.
Goats avoid and jump across powder snow.
Foxes, rabbits, endermites, and silverfish can walk on top of powder snow.
Shulkers and vexes are unaffected by powder snow.
"Snowier snow" was announced to be part of the Mountains biome in the biome vote at MINECON Live 2019, a joke teaser for powder snow.[10]
Cauldrons slowly fill up with powder snow when they are placed in a snowing biome.