The tip of the red giant branch (TRGB) offers a largely Population II–based standard candle whose H0 calibration tends to land near 69–70 km s?¹ Mpc?¹, intermediate between the higher Cepheid/SN Ia ladder value and the lower Planck CMB inference, raising the question of whether there is a genuine bias between TRGB and Cepheid scales or whether both are sampling different systematics (Freedman 2019; Freedman 2021). Within ΛCDM this situation is awkward because the TRGB method should, in principle, be less sensitive to dust, crowding, and young stellar populations, so its intermediate H0 has been interpreted either as evidence for subtle zero-point and population-dependent biases in the TRGB calibration or as a sign that late-time distance indicators as a whole may be more complex than the minimal model assumes (Freedman 2019; Di Valentino et al. 2021).