Frozen feeder food weird?

Hi all, it has been about 2 months now. I had 2 bags of baby rats for my corn snake in the freezer, and shes was going to eat her 2nd one in the 2nd bag today, but I noticed that one of the baby rats had a completely gray back looked like mold! or bacterial. Also all the ones around it had weird white streaks on them. So with out question I plan to throw these out and get her a new batch of food tomorrow. Or am I wrong was it not getting infected with some sort of fungal or bacteria?

They shouldn't have any mold/bacteria since they are in the freezer. Nothing can grow in there. Is it maybe freezer burn? I've had some mice and rats get that before. I still feed the mice since I know how long mine have been dead, as I get them from a friend. It's really up to you and what you are comfortable with.

Also, if it is freezer burn it won't come off. It could be a build up of ice, but if you scrape at it with your finger or a cuetip you'll be able to tell if it was fungal as it would come off