  Z. Xu, et al. [Phys. Rev. A 103, 023114 (2021)], have reported a measurement
for the enhancement factor $\kappa$, which characterizes the overlap of the
electron wavefunction with the noble-gas nucleus in Cs-$^{129}$Xe spin-exchange
optical pumping (SEOP), that is more than an order of magnitude higher than
previous experimental results and theoretical estimates. There is no plausible
proposed physical basis for this discrepancy. As the authors repeatedly
mischaracterize the nature and properties of the enhancement factor and do not
completely describe their experimental technique, there is little reason to
accept or consider this result in its current form in the context of future
relevant work on Cs-Xe SEOP and its applications.
