From September 2020 in New Zealand and South Africa and from October for all other global markets, the Google Play Music application will no longer be available for streaming music. Until December, only personal data, such as playlists and purchases, will continue to be available for transfer to YouTube Music. Google Play Music will then be switched off in December, but users still have until the end of December 2020 to export their personal content to YouTube Music. After that, the Google Play Music library will be permanently unavailable.
In addition, Google has further optimized and expanded the YouTube Music functionalities over the last few months. For example, it is now possible to edit playlists together with friends, control music directly from the Google Maps application or stream videos and songs on an Android TV.
Further information can be found here: https://blog.youtube/news-and-events/youtube-music-will-replace-google-play-music-end-2020/