The bug

In Java Edition, blocks of sculk will be randomly rotated by 180 degrees and/or flipped. Bedrock Edition, however, also allows sculk blocks to rotate in 90-degree increments, which Java Edition does not.

How to reproduce

Careful inspection of the texture. It'll become obvious after a while.

Alternatively, looking at large regions of sculk will reveal clear directional repetition artifacts from certain angles. As sculk is intended to be a chaotic block much like dirt and sand, such repetitions are undesirable and make sculk look more "ordered" than it should.

How to fix

A resource pack is attached to this ticket that fixes this issue entirely. The fix is simple - the blockstates file simply lists all rotation combinations with equal weights for both the normal and mirrored versions of the model.

Mojang have my full permission to (and are strongly encouraged to) use this fix.