There have been many news reports concerning a lecture delivered October 6 and printed in L’Osservatore Romano, by Father Uwe Michael Lang in which he discussed the views of Popes Benedict XIV and Benedict XVI on sacred music.
I’m happy to see the encyclical Annus Qui of 1749 get some attention (machine translation).
The document of 1749 says pretty much what Popes have always said: Gregorian chant is the music of the Roman Rite (because the text is the Mass and the music elevates the celebration) but other forms of sacred music built on its foundation are also permitted provided that they retain a sacred sense and do not displace the primacy of chant.
There is no surprise here, unless you have been reading implausible claims that the idea of “sacred music” was a 19th century invention and that chant has never been that big of deal.