What’s this unfamiliar app on my phone?

It's definitely worth looking into! Just to clarify, Honkai: Star Rail is a game, and if you didn't download it, check if anyone else has had access to your phone. But if you're the only one using it, it might have been installed accidentally. I would recommend uninstalling it just to be safe and checking your phone for any unusual behavior.

It sounds like you might have a mystery app on your hands! I know how frustrating that can be. Sometimes, apps can get installed through other apps if you've downloaded something recent. It's essential to check your recent downloads to see if anything suspicious popped up. Be sure to keep your phone secure!