About 90% of what people mean by "Vshojo bad" is really just some combination of anti-ing Nyanners, Veibae, and more recently Froot which they then smear the rest of the org members by association with.
Nyanners came with a built in anti contingent since she has a long history of internet celebrity, on 4chan in particular. She made her name in anime circles back in the early 2010s when it was one of the only places around you could get e-famous and a lot of the reasons why was she was a girl who made loli content. Most famously a song "Pomf Pomf" which is pretty much the loli anthem. Depending on who you believe she either thought it was all a big joke only to be shocked at the actual groomers it attracted, or was just in it for the cash and clout, but the result is she dropped her former fanbase hardcore and disavowed the whole thing - 4chan included - which burned a lot of people and cemented hard feelings ever since.
Froot is also from 4chan but on a smaller scale than Nyanners and /k/ (weapons/military larp) focused. Her controversy comes from allegations that she cheated on her military husband while he was deployed, serious business for the fanbase she cultivated at that time. She's generally behaved like and considered to be a backstabbing, sanctimonious narcissist behind the scenes which pisses people off, such in the Hogwarts Legacy twitter meltdowns where she basically approved of the harassment Silvervale (her corpmate) received.
Veibae is pretty much just the exact opposite of the Idol-style culture that made Vtubing a big thing and it rubs people the wrong way. She also managed a frankly impressive streak of insulting basically every established group in the scene early in her career which naturally pissed fans off.
The rest of the talents are generally considered below notice (Melody, Silvervale) or mildly approved of in isolation (Ironmouse, Haruka). Zentreya is interesting in that they're basically the only talent vtuber fans still make the "man using a voice changer" joke on since they exclusively use a TTS device to stream, so you'll see references to them being trans but there's no actual evidence either way. Hime Whojime is funny because she's a streamer who still gets advertised by the corp despite having done like two streams total in the past year and a half, general assumption is there's some sort of Trash Taste connection the corp doesn't want to get rid of. Or not. Your guess is as good as anyone's.
VshojoJP ruffled some feathers because they're both famous former Hololive talents. Nazuna was Rushia (responsible for one of the biggest yabs and infamous graduations in vtuber history) who is generally considered to be mentally ill but a pretty good streamer when she's not having a manic episode, but while she does have subtitles she streams exclusively in Japanese so you won't hear much about her unless it's drama. Kson was formerly Coco, also one of the most infamous graduations in vtuber history, but unlike Rushia she's looked back on very fondly. A lot of people are disappointed she's not as "good" or high-effort as she was previously and that she's too coombait these days, but generally the only people who seriously hate her are chinese bugmen and weirdos like Henri.
Vshojo the corporation also catches some hate for specific incidents. Most notable is the Nux/Phishing drama, where Nux Taku (at the time very close friends with most Vshojo talents) did an expose video on the corp where he claimed there was a group of scammers going around posing as official vshojo staff recruiting indies as cover to steal their money/ID, that Nux had informed Vshojo of this, and that they were doing nothing about it which represented a danger to the community he was morally obligated to inform everyone of. At the time of the release Nux claimed to have discussed his video with various talents and staff and got a green light to release it, but after he did and it blew up Vshojo released statements claiming the opposite and disavowed him claiming that he'd fucked up an investigation they were running into the identities of the phishers.
The other major thing that comes to mind would be the never ending Vshojo auditions, where they spent months and months advertising their recruitment of new talents from the indie scene that never actually went anywhere. When they finally did wrap things up it was to redebut Haruka Karibu as a new member, one of the biggest orbiters of the corp and someone who was already in pretty deep with the talents friend group. It had the air of a sham that left a bad taste in a lot of people's mouths and seemed confused and mismanaged as hell.
There are some other yabs but they're honestly kinda whatever and have the air of people who already don't like Vshojo looking for excuses not to like them further. Their dominance in certain award shows (biggest vtuber corp on twitch run by former founding twitch staff gets a lot of representation at twitch-based award shows, /vt/ in shambles). I've covered the major stuff that comes to mind first.
OH AND I ALMOST FORGOT: Vshojo's company tagline they use to advertise themselves with is "Talent Freedom". As in, the talents don't have traditional management and are free to do and stream whatever they want. Cue shitposting about whatever controversy or un-seiso behaviour a talent has gotten up to having "Talent Freedom"! spammed over it.
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