I have some spoiler thoughts on this and the tagging discussion, In my opinion changing the name tag doesn't really matter a whole lot. We never actually see the real Uika to my knowledge, she's not a relevant character, and is just a name that Hatsune stole. Plus in the band only Sakiko knows Hatsune's real name, the rest of their band keeps calling her Uika. In general it felt like the series swept the whole reveal under the rug, and it doesn't really matter. Though I don't play the mobile game so I don't know what occurs there, and I guess we'll have to see what happens with the next season of the anime. It would be interesting if the real Uika shows up to give the reveal some actual weight and meaning, because right now it just feels like a telenovela reveal that's actually a complete nothing burger for me.