I found this in an old home yesterday, the panel appears to be a fairly new 200AMP. There are smaller wires installed with the main lugs. The house has 4 different sub-panels, I would guess these go to one of those panels, not that it would make it any more correct.
I believe it to be an incorrect installation, but wanted to see what you guys said. The main panel also has about 6 or 7 free spaces left.
Sorry there’s no picture, I am having trouble with the upload. I will try again.