Is this uncanny valley 1) a fundamental nature of the higher frame rates, 2) a temporary phenomenon of 24fps-acclimatized eyes viewing 48fps, or 3) a temporary

Is this uncanny valley 1) a fundamental nature of the higher frame rates, 2) a temporary phenomenon of 24fps-acclimatized eyes viewing 48fps, or 3) a temporary phenomenon of fps technology getting ahead of costume/CG/etc technology that looks real at those rates yet? Or (I'm guessing) do we not really know yet?