  We attempt to clarify several aspects concerning the recently presented
four-dimensional Einstein-Gauss-Bonnet gravity. We argue that the limiting
procedure outlined in [Phys. Rev. Lett. 124, 081301 (2020)] generally involves
ill-defined terms in the four dimensional field equations. Potential ways to
circumvent this issue are discussed, alongside some remarks regarding specific
solutions of the theory. We prove that, although linear perturbations are well
behaved around maximally symmetric backgrounds, the equations for second-order
perturbations are ill-defined even around a Minkowskian background.
Additionally, we perform a detailed analysis of the spherically symmetric
solutions, and find that the central curvature singularity can be reached
within a finite proper time.
