Once upon a time, the Harry Potter fandom was rife with theories about the upcoming book releases. From shipping to Horcruxes, fans argued back and forth about what would be canon and what wouldn't. Queen of these debates was the author herself, J.K. Rowling. Any sort of tidbit about lore or history from the books was eagerly devoured by the series fans.
However, as the books released and time went on, Rowling's lore drops began to be more and more outlandish. Over time, J.K.'s status as Queen of Harry Potter has worn away, and some fans wish she would remain silent. She has now gained a reputation for doing more harm than good to the fandom that once venerated her, making her a bit of a ridiculous figure. To cut through that ridiculousness, let's see what are some of the craziest things J.K. Rowling made canon since Harry Potter ended.
Uncle Vernon's distaste for anything outside of the ordinary is well documented throughout the book series. From his casual cruelty of Harry growing up to his desperate attempts to keep him from Hogwarts, Vernon's antics bordered on laughable at times. So when the real-life Brexit referendum swept the U.K., one fan's observation of how Uncle Vernon might vote was confirmed by Rowling herself on Twitter.
This is a true-to-character thing to make canon, but it also adds an uncomfortable level of politics to a book series that shied away from real-world political actions. Given as well that Vernon would be well into his 60's or 70's at this point in his life, it's not something that fans necessarily care about one way or another.
It was a known fact during the series that prior to his post as Headmaster of Hogwarts, Dumbledore taught Transfiguration. So when Dumbledore was shown in Fantastic Beasts: The Crimes of Grindelwald teaching Defense Against the Dark Arts, fans became concerned.
No mention of this was ever made apparent in the book series and somewhat confuses the Harry Potter timeline. While it's not the most egregious thing J.K. has made canon, it's just one more brick in the wall J.K. has built between herself and the fans of her book series over the years.
Stern Transfiguration professor and Deputy Head Mistress Minerve McGonagall is a fierce character in the Harry Potter series. As a mentor and ally to Harry, she becomes invaluable to his fight against Voldemort. But J.K. released on Pottermore a long backstory detailing McGonagall's family history that managed to undercut her strength and resolve by making the key dilemmas of her life revolve around relationships instead of her accomplishments.
From a whirlwind but ultimately doomed-to-fail romance with a Muggle man to a short-lived marriage with a much older man who used to be her boss, it undercut McGonagall's tough and reserved exterior. While it's not bad to develop side characters and to give them relationships, the focus of McGonagall's entire backstory revolving around these lost loves changes how one views the character throughout the series.
Rowling has made it clear in multiple interviews how fortunate she was for the British welfare system when writing the books. As a poor single mother, they allowed her to provide for her family until the books were published. Perhaps that's why she announced that students at Hogwarts do not pay for tuition; the Ministry of Magic pays for all magical education expenses.
The issue with that though is that we see the Weasley family buying school essentials for their children throughout the series. Wouldn't wands and school supplies be a part of the tuition that the Ministry is paying for? While a charitable notion, it contradicts with previously established scenes throughout the book series.
One of the huge reveals of Fantastic Beasts 2 was the revelation that Credence Barebone might be someone else entirely. As revealed by Grindelwald, the young man is, in fact, Aurelius Dumbledore, long-lost brother to Albus and Aberforth.
This is outlandish for multiple reasons. Chief among them is that a tell-all book about Dumbledore was published by Rita Skeeter to embarrass his family name. If anyone were to have dug up that family dirt, it would have been Rita. Second, the timeline for his birth makes no sense. He is clearly younger than Albus, and given his approximate age, his father would have been in Azkaban and his mother dead. While it may prove to be a misdirect, it's still enormously canon-breaking on Rowling's part to have it mentioned at all.
The main antagonist of the series goes by many names over the course of the book. Tom Riddle, You-Know-Who, He-Who-Must-Not-Be-Named, and of course, Voldemort. Apparently, though, fans have been pronouncing Voldemort wrong for years. Rowling tweeted that the "t" at the end of Voldemort is silent, to better equate with the French word for "death".
The problem here is that Rowling herself has said "VoldemorT" multiple times over the years, and never corrected the studios' pronunciation of the name in the films. It's one thing to claim that the name was intended to have a silent "t" and you decided it sounded better with it. It's another to claim that you're the only one who pronounces it correctly when you yourself said it wrong for years.
Rowling once made waves when the books were still being published. In an exclusive interview, she was quoted as saying that Ron and Hermione should end up together. More importantly, Harry and Hermione fans missed "massive, anvil-sized hints" that it wouldn't work between the two according to the author back in 2005. Which is why a more recent announcement that Ron and Hermione's marriage was a troubled one rubbed fans the wrong way.
For one, fans who felt the pairing didn't make sense were already upset about the definitive "delusional" statement. And for fans who shipped the two of them, it was a betrayal of trust that two wouldn't get their happily ever after. By saying that the two fundamentally would have needed work to make things happy between them, Rowling managed to upset a large portion of her fanbase with one stroke of the (digital) quill.
There was enormous fan backlash when Fantastic Beasts: The Crimes of Grindelwald revealed an unsettling truth about Voldemort's pet snake, Nagini. Nagini was no pet at all; she was, in fact, a Maledictus, a human with a blood curse that allowed her to turn into a snake. Eventually, this transformation would one day become permanent, with no way of knowing when and where.
For many fans, the casting of a female who would be little more than a dictator's slave was a step too far. It created a troublesome relationship between the two, especially given that Voldemort somehow survived on Nagini's milk. As disturbing as that concept might be, it was one Rowling felt was necessary to add into the Harry Potter canon for good.
Due to it being a product of its time, the core cast of the Harry Potter series is all fairly homogenous. While this would be troublesome today, it was far more frequent when the book was published in the 90's and 2000's. So when Jewish fans inquired about whether Jewish wizards existed in the world, her reveal that several of them attended Hogwarts felt like an attempt to be inclusive after the fact.
Specifically mentioning Anthony Goldstein (a Ravenclaw wizard who was among the 40 original names Rowling wrote for the series characters) is problematic on a few levels. The sole mention of a single Jewish character (especially one with the last name Goldstein) felt like a cheap way of adding inclusion into the series postmortem for many fans. This one factoid from J.K. (along with the infamous Dumbledore is gay fact) began Rowling's slow descent into being seen as a fandom pariah.
Perhaps the most notorious instance of Rowling's canon interference in recent days was a Pottermore exclusive fact. According to them, wizards only adopted Muggle plumbing in the 18th century; prior to that, any waste was simply magicked away.
As you can imagine, this fact was not received well by fans. Mockery and outrage over the unnecessary information of the fact quickly blew up online. It quickly became the pinnacle moment of Rowling not knowing when to leave the Harry Potter canon alone. Since then, fans await not with bated breath as they once did for new facts and lore. Instead, they sit with an eye-roll ready for whatever else J.K. Rowling will deem necessary to add or change about Harry Potter canon. Where's Gilderoy Lockhart when you need him?