Cabin Air filter covered in soapy substance

I have a 2021 QX80 LUXE. We have had issues with the AC and major compressor noise. Dealership finally looked into the cabin air filter and it came back with a purple substance on it. They said it could be from a car wash or detailing. Has anyone ever heard of such a thing. It may have ruined the blower motor and they do not want to warranty it. I bought it very slightly used. Never had it detailed. Routine car washes. And I have clearly never changed the filter. Any guesses?