Perhaps it tells of the AntiChrist or False Prophet rising out of the Catholic church? I’m not Catholic, but hear me out here - if this were a revelation (which God would have allowed as a warning), the Catholic church would probably not want it public lest every pope be seen as an AntiChrist by the faithful.
I’m not Catholic, either. I have heard of Fatima before and never knew what it was about. This has peaked my interest as a Christian....and certainly in the times we are in at the moment.