Sometimes doing a thing one way is just common sense, but most of the time there is some innovation involved, e.g. GrapheneOS malloc. The code is covered by license, but are design decisions? Especially given the fact, that they were openly discussed before the code was written?
IANAL and my understanding is that in general ideas cannot be protected by copyright.<p>For instance, in general you may protect the creative text that describes a cooking recipe but not the recipe itself.<p>Some innovations may be covered by software patents where they exist, but if not then I am suspecting that it's either keep it secret or anyone is allowed to re-implement it.