Government setting prices like that is a terrible idea. The solution to this problem is competition. The only regulation needed are laws that stop Apple from preventing competition. If there were alternative app stores, free market forces will naturally prevent Apple from doing stuff like this. They'll be free to charge whatever they want, but customers and developers will also be free to go with a competitor instead of them.
Sure, Apple and their fanboys are going to say stuff like "it will be bad for privacy" and "Apple needs to control everything to protect us from malware", etc. Pretty much the exact same type of arguments AT&T was making before they got broken up in the ~80s. If that didn't happen, we probably wouldn't have gotten the internet as quickly as we did (or at all). That's a pretty clear example of how monopolies stifle competition, and how breaking them up can be lead to incredible innovation.
Hell, I don't think we even need new laws. I'm not a lawyer, but I'm pretty sure what Apple is doing is already illegal, since it's so obviously anti-competitive and detrimental to society/the economy. Even investors will probably be better off in the long run if all these tech giants have their monopolies broken up, since the new opportunities in the market will undoubtedly result in new innovations and better investment opportunities.
Also, I need to say this otherwise the conversation will get predictably derailed:
* Apple is bad
* Google is bad too
* Microsoft is bad too
* Amazon is bad too
* Meta is bad too
* <insert tech company here> is bad too