The bug

When at the exact center of the world, the patterns formed by bedrock appear to have a sort of imperfect mirror symmetry to them, rather than the complete randomness that would be expected.

How to reproduce

1. Teleport yourself to 0, -59, 0
2. Use a fill command to clear out an air space: /fill ~-20 ~ ~-20 ~20 ~5 ~20 air
3. Use a fill command to replace deepslate and other desired blocks with a lighter block to make bedrock stand out more: /fill ~-70 ~-1 ~-70 ~70 ~-1 ~70 white_concrete replace #deepslate_ore_replaceables

Expected results

The bedrock would just be random noise.

Actual results

There is definitely visible symmetry that can be seen in the shapes the bedrock forms, with occasional imperfections.