I'm just testing World generation on the Minecraft Snapshot 21w10a.

I tried playing survival and have noticed a considerable change on the world generation. Specifically on the surface of the world.

World Type Was Set As: Default

not that it has changed or anything, I've noticed a few problems.

(1.16.5 and before are perfectly fine and do not consist of these issues)

1) Floating Chunks 
First bug I came across

2) Patterned structures of stone etc. 
Now, this is pretty common on the surface. There are repeated structures of stone (Pretty common in the mountains biome as well). Also, there are walls of stone and grass that extend upwards as well. It looks really unusual and I know for a fact that this isn't normal.

3) Random floating blocks in the surface

4) Blocks intersecting underground structures mainly Mineshafts
A single layer of deepslate was dividing a proportion of a Mineshaft into 2. 

Those were all of the bugs I came across, And do note that none of these bugs were present in 1.16.5 and before. It's only this snapshot I've seen such bugs so far.

I think Smooth world generation would fix all these problems, And other than the bugs mentioned above, I haven't seen any other issue so far.