That’s called exposition, and when it’s obvious it’s being done it can be really bad.
Incidentally, I was just reading book 2 of a trilogy and rather than try to casually mention the events of book 1 here and there as a reminder—which a lot of books do—the prologue was a complete summary of book 1 written as a holy book from 1000 years in the future. It was a really cool way of doing it. Book 1 had chapter intros from the same future holy book, too, but have it as a big infodump was a great reminder of the story.
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