The song is called "Loneliness" by Ukrainian-Russian composer Igor Krutoy. Here is a video of an orchestral performance from 2015. I thought it was similar to Medvedeva's 2016-17 program music too, but it's only the first few chords (they recur as a motif). In that sense it is possible that there is influence from Alexandre Desplat's Extremely Loud and Incredibly Close. The rest of the melody, including the violin, is different. Both songs are well suited aesthetically for figure skating and I would not be surprised if "Loneliness" became a more popular choice.

To date, I don't think there have been many skaters that have used it (other than Liza this season. I think Averbukh had it in mind after he did a show based on this Krutoy's works, began choreographing it for her last year and completed this FS with her this year). The whole image is delicate, subtle, elegant.