Definitely odd, I’m seeing the same behavior you are. I’ll request for the team to look into this and open an issue if needed. In the meantime you can use the example URL format referenced in the docs as a temporary workaround.
For Grafana Cloud the URL will be https://$orgname.grafana.net/playlists/play/N where $orgname will be your Grafana Cloud organization name and N will be the Playlist number. The first Playlist created will be 1, second Playlist created will be 2, and so on.
If you’re not sure what your Grafana Cloud organization name is, when you log in to your hosted Grafana from the cloud portal the orgname displays in the URL. The Playlist number may get tricky if/when you create and delete Playlists but you can use the Playlist HTTP API to find the Playlist ID numbers if needed.
If you run into any trouble, just open a ticket for the Support team to assist!