I had been used to pressing the voice assistant button, and streaming whatever I asked for. Recently, it said, "you need to install You Tube Music first." I checked, and sure enough, it was gone, and it didn't seem that it was available to put back on. Then, inexplicably, I pressed the button and You Tube Music was back, and it also searched for the result on Spotify. I'm glad they're both available again, but I don't know why they disappeared.