The latest version of the Music app that's bundled with macOS 11.2 has made some changes to the description property of playlists. As you probably know, the description is a bit of text associated with the playlist that appears below the title and info area of a playlist in Playlist View. It can also be seen in a similar place on the iOS Music app.
In the latest version of Music, clicking a playlist's "Add Description" button opens a new panel that can contain a lot of text. If the playlist already contains a text description—say, an Apple Music playlist—only the first three lines of text will appear, followed by a "more" button that opens the panel and reveals the full text. And it's strictly text, no graphics.
Additionally, the description is now visible in Songs and Albums Views, whereas before it was only accessible in Playlist View.
While I suspect this will be used to accommodate more editorial content from Apple, there's no harm in using this vast text real estate for liner notes, personnel lists and such in your own playlists. Unfortunately, while there doesn't seem to be a limit to the amount of text the description panel accepts it doesn't scroll. I found this out when I dumped the entire Wikipedia article for ZZ Top into it and could only view what fit into the expanded panel. However, all of it is displayed on iOS Music. So, kinda neat.
Update, Feb 2, 2021: Kirk McElhearn apprises me that this was available in the previous version of Music as well. He remembers clicking it "by accident". Well, anyway...still can't scroll.