In this snapshot players fall through Powder Snow if they are wearing Leather Boots and have a falling distance of more than 3 blocks, to prevent fall damage.
However, Feather Falling increases the safe falling distance to up to 7 blocks - but you still fall through the snow.
This seems inconsistent with Slow Falling, because you don't fall through powder snow if you have that effect.

I'm not sure if this is a bug, since in theory whether or not we fall through snow would be determined by the speed, which is not decreased by Feather Falling. However, because the original report MC-205131 mentioned fall damage, it makes sense to only fall through the powder snow if you would take fall damage otherwise. At least this would make leather boots less of a pain in my opinion, since we are supposed to use them on mountains where feather falling is essential.