The quote you provided earlier from Scalia didn't say anything about 'acts' of Congress, just about citizenship being conferred by Congress. The 14th amendment would be a case of Congress conferring citizenship.
I quoted Scalia, who said, "But for constitutional purposes, it seems to me, as opposed to statutory purposes, whether the person is an alien or not should depend upon whether the person is a natural born citizen of the United States or whether citizenship must be conferred by Congress..."
The 14th Amendment is not an act of Congress conferring ["to grant or bestow"] citizenship. It is an act of the States, who voted by a super majority to amend the Constitution. Once amended, the CONSTITUTION makes everyone born here of parents under the jurisdiction of the US citizens.
Congress is granted the power of naturalization by the Constitution, and they pass laws (acts of Congress) defining how a person can become a naturalized citizen. In the case being argued, they had stricter requirements for the child of a father than for the child of a mother, and the Court upheld the acts of Congress as complying with the Constitution.
The 14th Amendment is the Constitution, as determined by the STATES, giving citizenship. The 14th derives its power, not from Congress, but from the STATES that voted to approve it. Congress drafts the wording. The states then vote to approve, or not. That is why the 14th Amendment has power, and the Equal Right Amendment does not.