My ducks are split up now too for random other reasons I have 8 outside and 4 inside its a circus act I have to move everyone to get the geese through and the chickens are stealing the ducks house during the day in frigid weather and ducks are NOT happy about that LOL
I hope you can get...
just in case if its frostbite read this article first
https://www.backyardchickens.com/articles/frostbite-what-to-know-about-injury-care-and-recovery.78168/
hey also are you keeping their water inside their house where they sleep? they don’t need water overnight inside their house, especially a heated bucket that would really humidify the air in there
i think frostbite starts at tips and edges? so I don’t think it’s frost bite. It looks like little cuts like you said . like that are trying to heal themselves by scabbing over or perhaps turning into Bumblefoot. but let me clarify that Im not frostbite experienced so I could be wrong...