Some tribes have been in legal battles over the past few decades because they’re trying to disenroll people no matter how “native” they are. IIRC at least one tribe was limiting membership to only the descendants of the families that signed a specific treaty and then only if they had the paperwork to back it up. Which, if you know anything about the history of natives in this country, is really fucked up to require.
Not the one I remember but here’s an example of a tribe disenrolling people regardless of their “blood quantum”: