  In a recent Letter [Phys. Rev. Lett. 129, 087001, (2022)], Masuki, Sudo,
Oshikawa, and Ashida studied a Josephson junction, with Josephson energy
$E_{\rm J}$ and charging energy $E_{\rm C}$, shunted by an ohmic transmission
line with conductance $\alpha (2e)^2/h$. Their model includes a realistic high
frequency cutoff of order $\alpha E_c$, that is typically smaller than the
plasma frequency $W$. The authors present a phase diagram showing surprising
features, not anticipated in the established literature [eg. Sch\"on and
Zaikin, Phys. Reports 198, 237, (1990)]. For $E_{\rm J}/E_{\rm C}$ above a
certain value, they find that the junction remains superconducting for all
$\alpha$, while below this value, they find that the insulating phase leads to
re-entrant superconductivity at small $\alpha$. In this Comment, we show that
their Numerical Renormalization Group (NRG) implementation is uncontrolled, and
that there is no evidence for the re-entrant superconductivity in the phase
diagram presented in Fig. 1a of PRL 129, 087001.
