One I recall that rubbed me the wrong way was one of her videos on "is being trans a social fad?"

One the one side you have people claiming that it’s a socially contagious fad among the brainwashed woke who want to mutilate your innocent children. On the other side there are those saying that it’s saving the lives of minorities who’ve been forced to stay in the closet for too long. And then there are normal people, like you and I, who think both sides are crazy and could someone please summarise the facts in simple words, which is what I’m here for.

Not super fond of the "both sides are crazy" idea when one side is arguing "people should have equal access to medical care and be left to live in peace" and the other is trying to legislate the former people out of existence.

She further goes on to platform ideas like "rapid onset gender dysphoria" which is based on spurious data gathered on a "parents of trans children" forum. None of the actual studies on the subject have supported the idea at all. The science is against it, yet she's presenting it like it's some "other side of the coin" nuanced take, and not just utter nonsense. It's a bit like lending credence to the idea that the Earth is flat because there's a whole group of flat-earthers out there who believe it is.

Ultimately though, I think my main reason for avoiding her is that she just doesn't post sources. They're all hidden on her Patreon, and I just don't think that's how it should work. I know educational videos aren't exactly scientific papers, but hiding your sources just strikes me as bad manners. If the goal is to educate and nurture an interest in a subject, why obscure the path you took to get it? It just doesn't make sense to me, and most other channels like hers do publish their sources.

Professor Dave has a lot of examples he's pulled from her videos as well as counter arguments.

https://youtu.be/vaZZiX0veFY

Edit: She's a right wing grifter who has been out of science for a while and is clearly very annoyed about it, because she came up with bad ideas and doesn't really know anything about most of the things she talks about.

Adding to what the others have said: I think Hossenfelder is also an example of chasing YouTube popularity. And apparently many people are really into this anti-science, right-wing stuff. It probably also aligns somehow with her own values, but I'm pretty confident that this is beneficial to her streaming business.