“Matsuri” refers to another Virtual Youtuber called “Natsuiro Matsuri”. The context here is that Matsuri is a vulgar person and she often makes dirty jokes with Tamaki. Luna just debuted recently and she seems cute and pure, so Tamaki was surprised that Luna hangs out with Matsuri.
My question is, what does「まつり落ち」mean in this context? Literally, I think it would mean “fall onto Matsuri”. Does this mean “fall to Matsuri’s level” or “to fall into the same position as Matsuri’s”?
Cool, I didn’t think anybody else watched Hololive.
I’m still very slow at reading so it would take me a long time to fully parse and understand the transcript. On Wanikani I learned that 落ち means “conclusion” so maybe that will help.
My best guess would be closer to the former. I think it’s ‘fall’ in the sense of something like ‘fall to the Dark Side’. It’s clear that it’s not a standard expression since the other YouTuber starts laughing and saying, ‘What is that even?’ I think it’s literally something like a ‘Matsuri Fall’ i.e. ‘fall in the manner of Matsuri’ or perhaps ‘be dragged down by Matsuri’. It’s probably something like a fall from grace.
The bit that you said you ‘don’t get’ is 扱い(あつかい)if I’m not wrong, which means ‘treatment’ (i.e. to treat someone/something as…). And by the way, I think it’s だけで, not だけど, meaning that the sentence should read something like ‘Why does just playing/having fun with Matsuri-chan Senpai mean I get treated like I have “fallen to Matsuri”?’
In popular vtubers’ videos, when someone says something that gets a big reaction out of someone else that you don’t understand, (or in general if someone says something you didn’t catch but you think someone might have found funny) I highly recommend looking at the chat (since it’s a whole bunch of native Japanese speakers watching the same video you are and reacting in kanji, which helps clear up mishearings)