Hell what’s I’d do is go back to the dealership and honestly I’d just look at the other 2021s that were parked on the line right next to yours and see if they have the same look. 

It looks like some kind of skin effect. Maybe from the molten metal touches the mold walls. But I would be talking out of my wazoo.

You should ask this guy. He's very experienced with aluminum casting, machining and engine building

https://myfordboy.blogspot.com/

https://www.youtube.com/watch?v=M95bhPrDwA0

I did talked to the sales guy and he said/sent me a picture of another 4Runner on the lot and have the same finish on it.  I don't really care what it looks like as long as it's not weakening the metal.

From the picture, it looks like molten aluminum was poured into a mold that wasn't properly pre-heated.  I hope it's still under warranty when it starts leaking.

So I looked it up a bit more closer, this is not the head, this is the timing cover, the timing cavity is not pressurized right? I suppose if it fails in the future, the leak won't be that bad? XD