https://github.com/SiEPIC/SiEPIC-Tools/blame/12974c7903a8bff5170096d8e7f09fb5263b3512/klayout_dot_config/python/SiEPIC/utils/__init__.py#L1080
Spikes are generated when used in the AMF PDK
Pcell parameters:
Bf=30
Reff=15
w=0.5
Bf=30

Bf=30.01

Bf=25

Bf=25.01

Only creates spikes for some round numbers, but you can see the points still don't match for perturbed numbers.