U.S. Constitution Article 1 Section provides that Congress has the power to enact Rules of Naturalization. Notice that it doesn’t say Rules of Citizenship. It says Naturalization, and it is the application of citizenship to those that do not have citizenship through natural means (NBC) or provided through the Constitution (founding fathers).
So Congressional legislation in regards to citizenship is a rule of Naturalization. Congress can only define citizenship requirements for those naturalized. This was done intentionally to prevent Congress from enacting law to revoke a NBCs citizenship.
Any law enacted by Congress to grant citizenship is naturalization. If you notice, there is no Congressional legislation for those born in the US, and having jurisdiction. The processes and requirements vary and are defined within the legislation. For example, Congressional legislation requires that persons born to foreign parents outside of the US must be a legal resident for 14 years and take a test and oath to get citizenship. And within the same legislation, require that all persons born to US citizen parents outside of the US to file paperwork x, y, and z to enact citizenship for their child at the time of birth. Both are processes of naturalization with different requirements for enacting citizenship, but both are resulting in naturalized citizens.
A nbc shouldn’t change with the times. When Cruz was born 10 year residency requirement.now 5 year residency...next year could be 1 year.etc