In some android phones you don't even need that checkbox anymore instead a android dialog will pop open to ask you if you want to install the app from a untrusted source...
Through might a a vendor specific change.
Also the idea that you must "protect" you customers from "external payment services which might grab you data" is ridiculous it's assuming the user is generally incompetent
and can't do any decision by themselves.
Warning them is a different matter.
Requiring a min app price of 5€ (30% cut) or 1.5 (100%) cut for apps with non apple in-app payment would also be understandable.
But having intentionally vague formulated rules for which if you brake them you often either get no usable feedback or are called by phone is not ok.
Calling by phone in such situations is not good service but a common strategy to prevent paper trails which could show abusive behaviour.
Through might a a vendor specific change.
Also the idea that you must "protect" you customers from "external payment services which might grab you data" is ridiculous it's assuming the user is generally incompetent and can't do any decision by themselves.
Warning them is a different matter.
Requiring a min app price of 5€ (30% cut) or 1.5 (100%) cut for apps with non apple in-app payment would also be understandable.
But having intentionally vague formulated rules for which if you brake them you often either get no usable feedback or are called by phone is not ok.
Calling by phone in such situations is not good service but a common strategy to prevent paper trails which could show abusive behaviour.