For anyone else who get's this error, please only use the answer above (hello-world-ai)'s answer. I've linked directly to it below. https://developer.apple.com/forums/thread/711148#818106022

In regards to the above comment about losing category rankings, that is sadly true. If you change your apps' category, you will be completely unlisted from the original category, and will have to start gaining ranking in the new category. Essentially your app is seen as being brand new, and will have to regain all it's rankings again.