The feature works as described for me. When I enable "Maximize Compatibility" the personal hotspot is 2.4GHz and when I disable it is 5GHz. I am running iOS 16.4 beta with iPhone 14 Pro.
In my testing one thing I noticed is if you had "Maximize Compatibly" enabled and a device is currently connected to the hotspot it will not switch to 5GHz immediately when you disable it. To make sure it switches 5GHz I first disabled Maximize Compatibility then briefly toggled "Allow Others to Join" off and on.
If that is not your problem then it sounds like a bug, and nothing that can be fixed in settings by an end user.
- Report the issue to Apple at https://www.apple.com/feedback/iphone/
- Contact Apple support or visit an Apple Store
- Try wiping out your phone and doing a clean install
- If you are still on iOS 16.2 try upgrading to 16.3, and when 16.4 comes out try it.
If you are trying to connect both your gaming PC and Meta Quest 2 through the iPhone Personal Hotspot you may have issues with 2.4GHz being too slow for Air Link streaming. Even at 5GHz I would not really recommend using Personal Hotspot and would recommend a dedicated wireless router instead.