Has anyone seen this. My batteries are changing color. I don't think it's dirt. Is it heat related?  Am I storing them incorrectly?  I usually store these in a hard case, protected by foam, and I also keep them on a open shelf.

Can you post a picture with the discolored battery and a normal one?

Was not able to attach photo before. These two have discoloration.

I only have two, and they have the same issue

Probably just heat. Do you pull them out immediately after a flight.  Removing them afterwards can reduce a lot of heat from AC and battery.

Did you get any error message which regards to the battery on the APP? Besides, I would recommend you also check the Battery status on APP.

How old are they?
It is hard to really tell but they don't look that discolored, any chance you can take a closer pic of them and with reduced glare?