Recently, Lad, Patel, and Pratap [Phys. Rev. E 105, 064107 (2022)10.1103/PhysRevE.105.064107] revisited a microscopic theory of molecular motion in liquids, proposed by Glass and Rice [Phys. Rev. 176, 239 (1968)10.1103/PhysRev.176.239]. They argued that the friction coefficient for a Brownian particle in a liquid should exponentially depend on time and derived an equation of motion for the particle's velocity autocorrelation function (VAF). The equation was solved numerically and fitted to the results of molecular dynamics simulations on different liquids. We show that this solution, obtained under the condition of zero derivative of the VAF at time t=0, is physically incorrect at long times. This is evidenced by our exact analytical solution for the VAF, not found by Lad et al., and numerically, by using the same method as in the commented work.