iOS requires user permission for each app to make local network requests (Settings -> Privacy & Security). So in theory this shouldn’t be possible, unless ByteDance came up with a way to bypass it that made it through Apple’s review process.
1. That wasn't a bug for "over a decade," as far as I'm aware. It was only introduced with an OS update
2. I could be wrong here, but it required you to already have created a root user with a blank password, which isn't possible unless you know how to trigger another bug that does it.