Speaking of D5...

In performance, the final "Vincerò!" features a sustained B4, followed by the final note, an A4 sustained even longer—although Puccini's score did not explicitly specify that either note be sustained.[6] In the original score, the B is written as a sixteenth note while the A is a whole note. Both are high notes in the tenor range. The only recording to follow Puccini's score exactly was the first, sung by Gina Cigna and Francesco Merli, conducted by Franco Ghione

https://www.youtube.com/watch?v=bZ9PGRmruoc&t=3s

It wasn't just the fourth Vincero, but correct me if I'm wrong, it was the added note between the B4 and final A4.... Sounded to me like a....

https://youtu.be/n2M78g4I1uM