I thought long and hard about it, and the only reason where it makes sense that she wants to leave and the others don't try that hard to stop her, is not necessarily the "company direction" but just how many holos were able to accept and adjust to this new direction - while she herself could not accept it.
Let's analyze some of the rrats (skippa this section if it's too long)
> too much streaming work
Shion took a hiatus and Gura only sporadically streams, Aqua herself only streamed sporadically for a while and she could easily have continued that path if this was her issue.
> too much bts work
Subaru learned to say "No" to a lot of that stuff in order to stop herself from overworking, to the point where she had a whole week free where she could laze around and relax.
It's definitely not a "graduation" worthy reason since the other girls would just help her say No if that was the problem once she told them she was thinking of leaving.
> too much idol stuff
Aqua doesn't hate idol stuff, Aquairo Palette for example is a love letter to idol stuff.
> too little idol stuff
Could be a small sticking point e.g. her last 3D Live getting some criticism for being too "old fashioned". Not necessarily graduation worthy, but small cut perhaps. Same with the cut down of 3D stuff even after getting a bigger studio.
> her management
Possibility is there. I haven't really heard her talk much about whoever her manager is, so they're probably not that close. But again, not exactly graduation worthy since she or her friends can tell Cover to change them.
Pekora has also complained before about holomembers doing more and more sponsor stuff, idol stuff and other non-streaming stuff and becoming distant from their audience. She mentioned it's not something she wants Hololive to become. Pekora herself tries to organize group events, the rabbitality project and stuff to capture that old Hololive spirit and is seemingly satisfied by getting box wins where she can.
But perhaps Aqua was far more saddened by the loss of that environment.
Aqua is an introvert after all, so she's far more comfortable talking to people in mulitplayer games like Minecraft. A lot of her early clips involved her pranking holos and laughing at them (neighbor wars, holo resistance etc.).
Nowadays most of her interactions are irl in studio and stuff, but the ones she mentions also tend to be with girls she already knows through games (Towa, Suisei, Pekora etc.).
She got to know most of her current friends through playing games together, and now that the SMP culture of Hololive is no longer a big thing, she might find it a little suffocating now that she meets most of the newer girls in the studio rather than in-game where she can be more "herself".
Most of the girls seem fine with just streaming very little and just getting passive income, while Aqua may have wanted to meet them in game and have fun, but isn't able to do that now that most of the holos meet irl for the first time.
This is something she cannot really change, as it involves the choices of other members.
There's also the China thing, which would probably not have been a big deal but may have served as a sort of "last straw" for her.
She was obviously not in favor of returning to Bilibili, but perhaps seeing Matsuri - who lived through the chinkout - deciding to return made something click in her head and go "This is not the Hololive I know".
Matsuri would have first hand knowledge about just how bad the harassment was, so her just agreeing to go there for a little extra money - and management pushing Aqua as well for it - may have made her think that there's nothing more to be gained from staying in Holo anymore.
She came to Hololive to hang out and make friends after all. And she made plenty, all of whom are very close with her and will likely continue to be that way. But she can't exactly create NEW bonds anymore. She's not gotten close to most of the new holos, and even the Pekora thing was accidental due to - again - a rare box event happening.
The two big Box events (MC hardcore and Ark) that Pekora organized very likely may have been for Aqua, to give her a taste of the "old Hololive" before she left. Especially because they were a month apart, and likely organized after Aqua made her graduation plans and reasons known.
I'm slightly concerned because this is the same thing Pekora complains about, and if she's gonna stop doing Box events next year idk if anyone else will ever take up her mantle...
She might be going through a similar thought process, but perhaps not enough to quit over it (at least not yet).
tl;dr : Aqua quit because box events stopped happening and everyone became distant, became harder to make friends because she meets most new holos irl in the studio and not in game where she can be "herself". It's not something she can change, and is something most of the other holos have no issues with.
