The bug:
When brittle ice is broken from cracking where an entity has stepped on it, adjacent brittle ice that was not stepped on cracks when near the affected ice.
Steps to Repro:
Place brittle ice
Place a brittle ice next to the previous brittle ice
Stand on one of the brittle ice until it breaks
Observed Result:
The block not stepped on cracks
Expected Result:
The block not stepped on is left alone
This is likely intentional, as the same behavior can be observed in Java Edition