To wit, the tweets basically point out that some of the NijiID doing a offline met up with the now-graduated NijiID Miyu Ottavia since they are in the same country and all (barring Azura Cecilia who are currently in Straya and possibly other IDs who live in area that isn't central aka Jakarta/Jabodetabek), and they kinda playing it around like they were being haunted by the soul of a shit-posting otter, but generally speaking its not really connected to the rest of the vagueposting where they probably just mentioned about needing some break and all.
On the second link, though, I did hear about this since some Nijifans on a place I was part of did talk about it. One of the talent, Derem Kado is basically not really feeling well because she felt like she has to essentially commit more to use her JP speaking expertise to get more viewerships and she would want to try to ya know, not use JP. She also mentioned some sort of internal issue (unsure if it was Nijisanji related or her own real life matters), but she said she don't want others to try speculating. So it might be just her being burn out.
Generally speaking, at the moment NijiID themselves are having a bit of issues with their lives right now and not exactly because of the Niji-related issue. Azura Cecilia is having issues with her home, Siska Leontyne is dealing with throat issue that rendering her lacking the ability to talk long, and other stuff that each ID talents couldn't easily mention except by vagueposting. There is possibility that they too aren't exactly enjoying the merge, but at the same time, they don't have anything that is damning enough for them to follow like Miyu and graduate (who did it partly because of her creative differences with Nijisanji post-merge), and would stay in the boat for now, until they believed they are ready to move on, or that things would change.
I mean, of course they probably gonna be feeling something when they lost their branch while the other competitor not only retain theirs, but also managed to hit way higher than everyone combined despite them being the first.