I bet the lore is that the girl in the yellow jacket is the older sister, while the girl with the styled light hair is the younger sister, and the other two are her friends. They're just introducing each other. ;)
@eromancer Short version is that these two are adversarial true immortals (death does not stick, any and all damage will be undone) several centuries after the inciting incident. It is canon that they still fight and kill each other regularly, but is strongly indicated to be a 'going through the motions' sort of thing or just how they choose to pass time since they also interact peacefully in the present. Shippers are all too happy to tint that as an enemies to lovers situation, which could implicate the ongoing violence as extreme S&M.
I don't see much of this pairing anymore. Most Labrynth yuri nowadays is Labrynth/Tearlaments Kitkallos of all people just because of one guy who is super prolific in drawing it.
"Ninguang pay me in... other ways"
Also, the fact Beidou refuse her pay so Ninguang can go buy an hairpin, and finally both going to browse the market during festival because hairpin should be bought and offered by Beidou.
Every lantern rites these two act like a married couple
Wish he’d hurry up and give at least some of the OnT main cast some XXX release with each other! Since the middle volumes he’s kept everything over there very PG.
I mean they do this "yuribait" constantly. Even this Lantern Rites you had Ningguang/Beidou, Ganyu with Keqing, Amber with Eula. And "pairs" like Navia/Clorinde, Mona/Fischl or Dehya/Dunyazard/Candance appear semi-regularly.
I call it bait, because HI3 was waaay more "gay" and Hoyo still insisted that every girl in that game was designed as "waifu" for player akin to dating sim.