Prologues are often just a section of backstory or setup relabelled as prologue. It ain’t foolin’ nobody, chum. Sorry. It’s just the same wine in a slightly different bottle. If it looks like backstory or setup, walks like backstory or setup, quacks like backstory or setup—then it’s Donald-the-Backstory/Setup-Duck. Setting it apart and calling it something else isn’t going to work. Here’s some advice on prologues: Mostly: Don’t do ’em.
There are, of course, exceptions. One popular exception is a prologue in a book in an established series. A prologue is sometimes used in such a book simply to bring the fans of the series up to speed for the current
There are other legitimate reasons to employ a prologue. But don’t use one if you’re just trying to sneak in backstory.
Hooked, Write Fiction That Grabs Readers at Page One by Les Edgerton