DT Swiss carbon rim discoloration

Hi guys,
I just cleaned the chain of my bike for the first time and experienced some kind of discoloration on the rear carbon DT Swiss Arc 1600 rim.
I used a completely normal chain cleaner (Nigrin brand).
Have you ever experienced something like this?
Is this a warranty case, or, in other terms: Is this just awful to watch or has the carbon taken damage?
Thank you!