Media keys stopped working for me after an update and then started working again suddenly. I checked the version and it's 1:220.127.116.11.gb45d2a6b-10. I don't know if the client was upgraded or a dependent package was upgraded.
The latest snap update 18.104.22.168.gf614956d-16 is not with media keys too on Kubuntu 19.04. It worked with the previous versions (but that couldn't play local files due to a bug). Spotify doesn't show up in the media player widget