Although I could put this one under the section about messing with the canon, I felt like it deserved its own moment. The reveal that Credence is actually a Dumbledore is a really strange decision. Mostly because Albus only mentions one brother in the Harry Potter novels, and if Aurelius really ends up being the right-hand man of Grindelwald, you'd think he might bear a mention at some point. Sure, you can explain it away, say that Grindelwald might be lying, but Ezra Miller himself said it's very likely real and that we'll get an explanation for it at some point. But I'm already prepared to dislike whatever explanation we get. It's the complete invention of a character, and I think it's really messing up the Harry Potter books.