Mumei talks about her long absence (Hololive clip)
I'm not returning to my regular schedule for a long time. It is for me. I'm basically working on myself.
If this was a regular job I honestly would've quit. And I'm just very grateful that I have this opportunity and I really wish everyone could do this. I wish everyone, if they needed to, could take time away and just focus on themselves. It's horrible that life isn't like that for most people.
It was quite rough for me for a long time, and I just kind of just kept pushing it down "I'll deal with this later, I'll deal with this later, I'll deal with this later" but it went to the point where I gotta deal with this.
Especially in light of recent events from Niji, it's really nice to know that Cover treat their members better and allow them to take the time off they need
I quite heavily suspect her working on her own well being is somewhat linked to Selen/Dokibird suffering horribly under Nijisanji. She mentioned the two of them being friends early on after debut so I would not be shocked if seeing her friend suffer made her reconsider her own priorities.