It is shown that the cosmological redshift can be explained from a secular variation of the speed of light. Hubble's law is derived by assuming that the speed of light decreases with time, but remains constant in transit.
Arjun, T. T. (1970). A Heuristic Derivation of the Perihelic Precession. Chinese Journal of Physics, 8(1), 24-25. https://www.airitilibrary.com/Article/Detail?DocID=05779073-197004-201310040010-201310040010-24-25
TRENCEVSKI, K. (2003). NEW APPROACH TO THE FRACTIONAL DERIVATIVES. International Journal of Mathematics and Mathematical Sciences, 2003(), 315-325-022. https://doi.org/10.1155/S0161171203206050
Daif, M. N. (1991). WHEN IS A MULTIPLICATIVE DERIVATION ADDITIVE?. International Journal of Mathematics and Mathematical Sciences, 1991(), 615-618. https://doi.org/10.1155/S0161171291000844