Most states do require by law that you do this in a very short period of time after moving. (Although yes, it is not uncommon for people to violate this)
I agree, it's quite odd that you never officially register as a resident of the state, but I guess it's part of the US's aversion to "papers please."
My municipal tax authority and the US State department may have very different standards for validating “residency” and very different reasons for doing so.
My state (CO) semi recently hit a morph of this concern because they had "pioneer" license plates that cost an extra $100 or so and were only available to people who could prove N generations of ancestry in CO. The feds struck that down as .gov services provided being dependent on state origin and therefore against the interstate commerce clause.
That said, Florida can take Rep. Boebert back at any point.