Serenity Caldwell wrote on iMore explained why Apple Music adds DRM tracks.
Just like every other streaming service, Apple adds a DRM (digital rights management) layer to its streaming music collection. This keeps you from getting a subscription, downloading a ton of music in month one, then canceling the subscription. Instead, if you cancel Apple Music, all that streaming music becomes inoperable. […]
Then, any songs it can’t match, it uploads directly to iCloud; when you download a copy of those songs on a different device, you’re getting the same file you had on your Mac.
So what gets DRM? Any matched track you download to another device. It gets DRM because the file itself is coming directly from the Apple Music catalog, which, as we established above, has DRM on it.
Uploaded tracks that you re-download will never get DRM, because they’re not coming from the Apple Music catalog.
Mass panic because “journalists” jumped to conclusions instead of investigating before they write.