Refrigerant would come out as a "gas" mixed with oil ( would leave an oil stain ) that appears to be possibly soap ( dealer cleaning? ) or salt stain.
The refrigerant lines will get very warm when a/c is being used.. Something dried on the lines..
Feel pretty confident that it is not from a/c
I agree with the not Freon theory. It being so close to the ports is what made me think. It could be salt possibly. There isn’t really anywhere around here to drive into saltwater and it hasn’t snowed here in a few years so no salt on the roads.