I was playing in a single-biome taiga world and noticed that in the height range in which rain transitions to snow, there are blocks that receive both rain and snow. To be more specific, snow layers accumulate on the blocks, but rain sounds also play on the blocks. Additionally, both snow and rain particles appear over the blocks, although the rain particles only appear on the top surfaces of the blocks and can't be seen falling like the snow particles.

To reproduce:

1. Create a creative superflat world with cheats enabled using this preset:

   minecraft:bedrock,230*minecraft:dirt,minecraft:grass_block;minecraft:taiga

2. Run "/weather rain"
3. Explore the immediate surroundings
   → Rain sounds are playing although snow falls and accumulates on all blocks. Rain particles can also be seen briefly appearing on top of some blocks, even if they are covered by snow.

The world is set so all precipitation hits the ground at y=168, which, from my experience, is the lowest height in which all taiga precipitation falls as snow as of 21w43a. This means that there should be no rain and no rain sounds in this world unless you dig down.

In the picture I attached, the sound subtitle "lluvia" means "rain." I was not able to get screenshots of the rain particles because they disappear very quickly.