When running/walking and jumping on snow layers at the same time, you still make the running sound, even when you are in the air. I guess this is due to the fact your legs are sharing the same block as the snow layer, so you are still technically touching it. Just a minor thing that kinda bugged me.

This also affects particle affects. Also, running on snow layers creates brown grass/dirt particles, not snow particles, and the white particles only appear when you are mid air.

I have attached a video of this happening, as well as a comparison of this on grass blocks. It was recorded on 1.17.1 release candidate 1.