Found at “Hyrum’s Law” on 2022-10-21 10:54:50.

Not all consumers depend upon the same implicit interface, but given enough consumers, the implicit interface will eventually exactly match the implementation. At this point, the interface has evaporated: the implementation has become the interface, and any changes to it will violate consumer expectations. With a bit of luck, widespread, comprehensive, and automated testing can detect these new expectations but not ameliorate them.