Well there's the stuff I personally dislike. Like the Elon cringe skits she does, or the super weird uncanny valley face filter.

But the biggest issue is she didn't stay in her realm of expertise. She might know a lot about certain things, but then also talks about other stuff with the same level of authority. No caveats, no this is my opinion, she present it as fact. But the fact is she is really really wrong about a lot of shit. And just mixing and matching shit you know and shit you don't know is a big no-no in science communication.

One of the most egregious thins she did was make a video about trans folk and talked about it like it's a fad or even a disorder. She was not only factually wrong, she was spouting anti-trans propaganda. When called out she kept the video up and didn't do anything like a follow up, correction or apology. She has some really boomer views about a lot of things and then presents it like it's fact. Another panned video was the one about neurodivergence (autism) and there are more like that. There are multiple hour+ video essays about how she is wrong in these cases and they are worth a watch imho.

The annoying thing is, I don't really know what she actually does know. Because she mixes everything and doesn't stay within her knowledge base, now everything is suspect. So even the videos about physics where I think she does know what she's talking about, I can't trust. And even in physics it seems like she's very hit or miss, I spoke to somebody at a party once that did his PhD on one of the physics topics she covered in a video. He said she was like 10 years behind the times and was wrong about several key facts. Some of these were just wrong because of simplification, which might be excused given the format, but others were plain wrong. Now I don't know enough about the subject to make a judgement, but the dude I spoke to seemed to know what he was talking about.

Science communication is really really hard and it's a skill not a lot of people have. Look at how big the teams of researchers at for example Kurzgesagt are and even they mess up once in a while. But when they get called out, they go back and delete the video or better yet post a follow up or recently even a replacement video. And they qualify things with sources and caveats, mentioning which parts are fact, consensus, speculation and opinion. They also make it very clear at the beginning of the video what a viewer can expect. That way we can qualify the information and know what in what light to put the information presented. Now I realize Kurzgesagt may be one of the best channels when it comes to short form YouTube video science communication out there and it isn't fair to hold everyone to that standard. But there needs to be at least some level of due diligence involved imho.

I'm sure I left out some other stuff, there is a lot to find if you look for honest critique. I'm sure there's also a lot of unwarranted hate out there, but also a lot of stuff that's warranted.