Comment on "Non-linear interactions in cosmologies with energy exchange"

This work provides a critical reassessment of the cosmological models presented in the article "Non-linear interactions in cosmologies with energy exchange" Eur. Phys. J. C 80, 120 (2020) arXiv:1907.06410 . It points out and corrects several mathematical inconsistencies in the original article. These include a flawed simplification of a Li\'enard-type equation, unjustified omissions of integration constants, and an incorrect use of the variation-of parameters method. By deriving the exact analytical solutions, it is shown that the corrected mathematical framework fundamentally contradicts the claims of the original article.