My understanding is that certain specific services and types of apps are exempted from in-app purchases, such as those that use a subscription model (Netflix, D

My understanding is that certain specific services and types of apps are exempted from in-app purchases, such as those that use a subscription model (Netflix, Disney+ et. al.) or apps that are for real world purchases (think Amazon, DoorDash, etc.). Games and similar apps are not exempted in this way and thus are required per Apple's license agreement / developer agreement to use Apple's in-app purchases mechanism.