if you can, put the side stand up and have a look at the clearance between the chain
and the nasty hook on the side stand spring. If the side stand spring is installed with
the end of the hook facing up, (when the side stand is up) there is a possibility it will have negative clearance
with the chain... especially if the chain is a tiny bit loose.
That hook is in a perfect position to cause the damage seen in your very clear photo.