Analog film photography and cameras

(...) its like the paper backing has been stuck to the emulsion. Only the last 3 frames survived, although on close inspection of the negatives there is a faint hint of the numbers from the paper backing on them too.

Is there indeed paper on the negs or are the numbers just exposed on the film?
I had this once when I got a 120 out of the camera in bright sunlight (protective wrapper not shielding the light enough).