On July 19, 1952, Palomar Observatory was undertaking a photographic survey of the night sky. Part of the project was to take multiple images of the same region of sky, to help identify things such as asteroids. At around 8:52 that evening a photographic plate captured the light of three stars clustered together. At a magnitude of 15, they were reasonably bright in the image. At 9:45 pm the same region of sky was captured again, but this time the three stars were nowhere to be seen. In less than an hour they had completely vanished.
The third option, radiation damage to the plates, sounds the most plausible to me.
It would pre-expose the plate in the same manner as a double exposure in a roll of film so the “stars” would have already been on the plate before use.
We could point the JWST at it just to be sure though.