Oxidized flavor

[hedgehogbrew]

I am drinking a mild that I kegged a week and a half ago and it has a strong oxidized flavor already. It was a no chill batch that was in the fermentor for 2.5 weeks and then to the keg. I cannot figure out where it is coming from and so quickly. I purged the keg before filling.

Could it be from transferring hot wort into the cube for cooling? Or could it be from old malt?

Any help would be appreciated.