Comment on "$Z_c$-like spectra from QCD Laplace sum rules at NLO"

In Phys. Rev. {\bf D103} (2021) 074015 (arXiv:2101.07281), huge (or largest) mass gaps between the ground states and first radial excited states for the tetraquark molecular states are obtained, $\Delta=1.70\sim 2.35\,\rm{GeV}$. We explore the problems in the operator product expansion, Borel windows, etc, in details.