I think something else that annoyed people was that she made sustainability her brand but she clearly never believed in it.
Like she was thrifting since her early videos but I don't think it was ever about sustainability until that became a trend (honestly, the rate she thrifted at and the number of clothes she used to own should have been a hint!). Then she did the Amazon ad which really put people off her because it was actively against her brand. She ignored anyone pointing out her hypocrisy, switched off comments on that video and never mentioned it again.
I also think the fact that you can't critique her without a million stans coming for you is off-putting too.
Overall I think some of it was the J-Law effect. She tried so hard to be quirky and relatable and played up that side of her persona - supposedly living in the sticks growing up, being a broke student, being open about sex and misogyny, self depracating Jones etc - that eventually people saw that it wasn't genuine. If you ever saw that behind the scenes video where she spends literally minutes trying to get a joke out *perfectly* and restarting over and over again, you'll know how much of her personality was a performance. (It was really bad, felt so sorry for her.) And we still expect some genuineness from youtubers despite knowing that some of it must be for show.