They didn't become reprobate; they already were. God "gave them over" (i.e. abandoned them) to the wickedness they wanted.
I'm going to wade into the minutia, cuz, hey, what is triple F for?
I agree that the verse in ? does not say "became".
But "reprobate" has a definition:
"No more chances" , jelly on the b.shelf n all.
I am aware that we are going to disagree on this next point. But you have a good idea what I believe on this, and I know what you believe, as I have read much that you have said.
So... Romans 1 appears to point out a progressive descent into Reprobacy, a state, like Grace, which is irrevocable.
We find "became" in verse 21, followed by "became" in verse 22, "changed" in 25, "change" in 26, and "leaving" in 27.
So Progress is the natural assumption.
Romans 1:21-27
Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.
Professing themselves to be wise, they became fools,
And changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.
Wherefore God also gave them up to uncleanness through the lusts of their own hearts, to dishonour their own bodies between themselves:
Who changed the truth of God into a lie, and worshipped and served the creature more than the Creator, who is blessed for ever. Amen.
For this cause God gave them up unto vile affections: for even their women did change the natural use into that which is against nature:
And likewise also the men, leaving the natural use of the woman, burned in their lust one toward another; men with men working that which is unseemly, and receiving in themselves that recompence of their error which was meet.
Cause and effect are plainly shown here.