“Birthright citizenship” is not required by the Constitution but neither is it prohibited if Congress were to allow it. What’s done is done, fix what is to come. In general, ex post facto laws and taxes are the epitome of unfairness and injustice (unless they are tax cuts ).
Here, @CWolf, let me give you an example of drawing the line where it may not have been “fair” (you apparently buy that "fair" nonsense the left is always claiming).
Some years ago, Social Security was modified to extend the graduated period for claiming full benefits: “Those born after blah, blah, blah, cannot claim full benefits 'till blah, blah, blah” . . .
Let’s say the born after date was April 2ᴺᴰ, 1947. I was born on April 3ʳᵈ, 1947, just one day over the line. Was it “fair” to me? The left would have me think so. I would call BS . . . NOTHING in life is fair, and if you think so, you’re a leftist.