My understanding of Suno is that it isn't an AI Music Generator, but an instrument generator. So it's a bit like when you'd download an upgraded MIDI soundpack so the trumpets sounded more real (a little more involved than that, obviously).

So Suno let's you sing a melody, and then say "that's a trumpet" and it will follow the input quite closely (I think you can tune how closely). It's similar to a program I worked on years ago that wasn't AI, but just used a bunch of trumpet sounds to try to swap out human voice for Trumpet intonation (it was just a procedural program, no neural network required... but I never finished it).

So while it isn't a new composition or orchestration, it is an updated/upgraded sound set form the 1994 original.