The only thing that I see that is wrong with spaces is in the bug that won't allow the parent space to disappear. For example, when I uncheck the "Allow multilevel hierarchy (experimental)" box in the spaces settings, there is still a "parent space" area when creating a new space. If I delete this "parent space" item in the forms app, will it cause any trouble? I don't know if it will solve the problem.

Edit: By disabling the options in the spaces settings, it should remove what it created.