Looks like a different bug from the other chunk flicker incidents, so i'm moving it here instead.

Originally posted by @Omgise in #142 (comment)

Should be fixed in 3.0.0 beta

Yes, 3.0.0 beta fixed it

@Omgise please try setting DISABLE_BLOCKING_CHUNK_UPDATES to true in falsetweaks.cfg, threading category, and see if it still happens.

Still happen

Snowflakes no longer flicker after Notfine is removed

This appears to be related to multithreaded chunk rendering. In vanilla anything using a Block instances minX, maxX, minY, maxY, minZ, or maxZ is not thread safe. setBlockBoundsBasedOnState gets called once per block at minimum in RenderBlocks, and in the case of layered snow that changes the maxY. shouldSideBeRendered is called after, and NotFine makes it use the maxY value that was set just before when determining if face culling should occur.

I would suggest rolling back to NotFine 0.1.0 for now.

Angelica implements ASM to make those calls thread-safe which means Angelica's implementation of threaded rendering should just Work™.
Be wary: Angelica is still in alpha so be careful what you do with it

I've ported over the minmax threading fix from angelica to falsetweaks in a local branch, so this bug will finally be fixed in the next update.