Irrelevant for tax purposes. There is no change in the federal income tax treatment of alimony and separate maintenance payments that are required by divorce agreements executed before 2019. As such, alimony payers take a deduction while alimony recipients include the payment in income post-2018.
However, for any divorce or separation agreements executed in 2019 and later years, alimony will no longer be reported on the tax return. This is also the case for prior agreements later modified to state that the new rules apply.