Snow Layers placed by Structures are overwritten by the snow layer feature, forcing their layer count down to 1

If a generated structure places snow layers, those layers can be overwritten by the vanilla snow layer feature. If the block placed by the structure had more than 1 layer, this blockstate will be lost when the feature overwrites it.

An example datapack with an example structure has been provided, as well as screenshots of how the example structure should look vs. how it looks when it spawns in a snowy biome.

First screenshot: The template of the structure, containing many different levels of snow layers.
Second screenshot: The structure naturally spawning in the Plains (it spawns correctly).
Third screenshot: The structure naturally spawning in the Snowy Plains (its layers have been removed by the snow feature).

Steps to Reproduce

1. Start a new world with the provided datapack

2. Run the command /locate structure example:snow_layer_structure_normal and go to the structure. It spawns in the Plains, and everything works correctly.

3. Run the command /locate structure example:snow_layer_structure_bugged and go to the structure. It spawns in the Snowy Plains, and assuming it spawned in a location with a natural snow layer, the structure’s multiple snow layers will all have been reduced down to 1 layer apiece.

This may seem like a non-issue, but some custom structures may want to spawn with layered snow to achieve a certain desired effect, and this bug ruins that.

Potential Fixes

• Make it so the snow layer feature doesn’t do anything if there’s already a snow layer at that location

• Cause the snow layer feature to add a single layer if there’s already a snow layer at that location