The bug

The model for four stacked snow layers defines a 16x8x16 pixel cuboid for the lower half of the block. As it turns out, this is completely redundant, as the bottom-half slab model does the exact same thing, yet the four snow layers model doesn't use the slab model as a parent, despite there being no visual difference in-game if it did.

It is worth noting that eight stacked snow layers uses the full snow block model instead of defining a dedicate "16 layers of snow" texture, so this is also somewhat of an inconsistency (even though there is no "snow slab" model for the blockstates file to refer to like it does for the fully stacked snow).

How to reproduce

1. Compare four stacked snow layers to any bottom-half slab
   1. Notice that they are the exact same shape
2. Look in the models/block directory of minecraft.jar
3. Open any bottom half slab's model
   1. Note that it references slab.json
4. Open slab.json
5. Take note of the shape it defines
6. Open snow_height8.json
   1. Note that it defines the exact same cuboid shape, rather than just pointing to slab.json as a parent model

How to fix

Attached are two resource packs which completely fix this issue. snow-fix-lite simply repoints snow_height8.json to use slab.json as a parent, whereas snow-fix-ultimate also completely fixes the slab side of MC-235694. The latter fix is preferable to make models more intuitive, but the former will be a bit quicker to add.