Is this just the paint cracks?
It looks like a chain jam from a wrongly adjusted rear mechanism. The paint finishes on these bikes tends to be fairly hard and a good smack will chip the paint.

The next question is what's been done to the frame. Without testing, x ray type inspection, history etc. Its impossible to tell. So that just leaves whether you trust it enough not to lay out for a new frame. Me, I'd trust that sort of catch if there is nothing obvious in the carbon layup and it rides ok. Go easy to start, build confidence in it; or not. You decide.