Is the husband considered sinful and unjust if he gives his current wife more gifts and a higher monthly allowance than he used to give to his previous wife, whom he divorced with an irrevocable divorce?

Islamic law mandates justice between wives, which is obligatory in cases of polygyny, and applies to lodging and maintenance, as stated in the Quran: "Then marry such women as seem good to you, two, three, or four; but if you fear that you will not be able to deal justly [with them], then only one." However, if a man divorces his first wife and only the second wife remains under his marital bond, he must provide for her sufficiently. There is no blame on him if he gives her more than he used to give his previous wife, as Allah says: "Let a man of wealth spend from his wealth." The warning against favoring one wife over another does not apply to him, as it is specific to cases of polygyny. There is also no blame on him for treating his second wife better than he treated his first wife, and this is not even required of him even if both were simultaneously under his marital bond.