With Mo Chen and An Xiao, then Qing Su and Feng Yi; Dreamtonics has released pairs of Chinese voicebanks with very similar singing styles. With the An Xiao, it felt like they were responding to the lack of masculine voices; but this logic doesn't make sense for Feng Yi. I have two theories right now:
1. They are covering different dialects (something that's much harder to pick up on if you don't speak the language), or adding features that are hard to update the original voicebanks with
2. It's become difficult to source voice providers with varied voicetypes - soft pop is probably the most common professional singing style, so would be the easiest to come by. Fear of being replaced was a problem even during the early days of Vocaloid, so the realism of AI could make hiring singers even harder. The voicetype we're hearing currently sounds a lot like the AI equivalent of the many Kokone-type voices that boomed during V3, it's giving me a case of deja-vu.
*edit*
Her vocal modes are Chest, Power, Open, Soft, Airy, and Opera. I'll be very interested to hear them, as this will be the key thing that sets her apart from Qing Su.