Deterministic redstone wire is biased to going upwards

Steps to reproduce

1. Connect 2 pistons together with redstone wire with both pistons connected to redstone wire that doesn't go up
2. Connect the same pistons together with a separate wire that goes up for one piston
3. Power the pistons with both wires in a spot that creates randomness and observe how the redstone wire that goes up isn't random

Observed
When the deterministic redstone wire experiment is enabled redstone wire is biased to going up blocks.

Expected
When the deterministic redstone wire experiment is enabled redstone wire is unbiased to going up blocks