Powder snow is one of the tricky new features in Minecraft 1.17. Powder snow is naturally generated in areas with snow and it seems to be indistinguishable from regular snow, so naturally the only way to find it is to stumble across it literally.
Fortunately, there is an easier way. To get powdery snow, place the cauldron in the snowy biome outside when it snows. The cauldron will be slowly filled with Powder snow. After it is filled, you can right-click the cauldron to get a bucket of snow powder. For using it to right-click on the ground to create a block of powder snow. The powder snow block cannot be removed; you can only retrieve it again by right-clicking the block with the empty Bucket.
As for what powder snow actually does: it is a trap block. All entities (including players) will sink into the powder snow block if they walk on it. After being in contact with the block for 7 seconds, the player will begin to suffer freezing damage (1 HP for 2 seconds).
During these 7 seconds, you will see frosty vignetting on the edge of the screen, indicating danger. Fortunately, there is a defense: leather armor. Any piece of leather armor will counteract the freezing effect. If you wear leather boots, then you won’t fall through the powder snow.
Before closing this article, there are some things worth knowing. First: The powder snow will melt when exposed to fire, which is expected. Second: Skeletons trapped in powder snow long enough will become Stray(Ice Skulls). Even if the previous skeleton is damaged, the Stray will spawn at full health. Very interesting, right?