It changes a lot, since as an independent entity Apple Music (for example) is answerable to its own investors and board of directors, including having the pressure to be profitable. Right now Apple can subsidize them for as long as they force all competitors out.
But it is standard practice for divisions to bill other divisions for work. I would be almost certain that Apple Music is already paying the 30% tax however since it’s internal it doesn’t really make a difference. Likewise splitting into a new entity does not change anything.