Loaded the “Time of Day” map preset. Facial hair and eyelashes card glow by default (1st pic).
Disabling the volumetric clouds appears to fix it, as does the disabling the sun. Only appears to affect the hair cards (not strand or mesh hair) and only beards and eyelashes. Seems to happen at any sun position when the sun is occluded by a volumetric cloud but not if the sun is unobstructed.
Mesh Beard: (This LOD looks awful btw)