IOS has already gotten the option to turn the fullscreen art on and off, but android hasn't. The fullscreen art cuts of the corners of the song/album cover art and has a grey bland looking filter to make it look even worse. It's been like this for months and I don't see any good in it. Here's a quick example of what it should look like vs. what it looks like with the fullscreen album art.
Updated on 2019-08-07
Thanks for bringing your idea to the Ideas Exchange. It is possible to turn of Canvas on Android. You can do this by going to Settings > Playback > Canvas (turn off).
Let us know if that helps! Have a nice day