Trust me, Its the cheap stuff from China or Friends, The finbox in question is the side finbox, I have dozens of pictures, pictures of the fins without a scrach, all that is past now, my problem now is how to correctly fix it with surfboard repair labor.
Some say I have to remove the box completely.
Some say I cannot use the same box because it was sanded etc etc...
I removed part of the deck to check for cracs and didnt find any.
There is one suspition I need to check: maybe the finbox has a leak and the water that got inside was the responsible for the whole finbox area to soften.