So it's more like, they just choose to not label themselves, maybe considering the anties and their shit they've been pulling lately (just follow the Aloe situation and I wouldn't be surprised why they've decided beforehand not to reveal anything explicit).
What's the Aloe situation.
She's actually an upcoming vtuber from Hololive that got terminated/quit herself because she apparently 'leaked' her live2D models before her debut was supposed to happen (she posted a stream on twitcast with her live2D which was supposed to be monitored by her manager and she forgot to delete it) and there were rumors she had a boyfriend, which she denied and asked the 'fans' to stop harrassing him as they are just friends. This was just the beginning as antis proceeded to doxx her phone number and her adress and started harrassing her. Basically the company behind Hololive blamed Aloe for what happened and suspended her shortly after debuting for two weeks. Those were almost over when the statement came from Hololive that she'd be retiring from the company.
I'm kinda glad that the company behind Nijisanji (where both Kana and Tomoe belong to) responded to this with measures against online harrassment and hired/arranged a company to watch over them and create an online report system so if they were harrassed they could report it. I'm still very hesitant about their safety still, even though these measures were put into place. They can be this happy together and open because they can preserve their anonymity.