Can you provide a source this? To my understanding, the GnuPG project (and by extension PGP as an ecosystem) considers itself very much alive, even though practically speaking it’s effectively moribund and irrelevant.
(So I agree that it’s de facto dead, but that’s not the same thing as formal deprecation. The latter is what you do explicitly to responsibly move people away from something that’s not suitable for use anymore.)
I would be very much surprised if GPG has ever really achieved anything other than allowing crypto nerds to proclaim that things were encrypted or signed. Good for them I guess, but not of any practical importance, unlike SSH, TLS, 7Zip encryption, etc.
(So I agree that it’s de facto dead, but that’s not the same thing as formal deprecation. The latter is what you do explicitly to responsibly move people away from something that’s not suitable for use anymore.)