I can understand disabling the comments section, but for playlists I would've expected that you could only make playlists with all videos from the kids section,

I can understand disabling the comments section, but for playlists I would've expected that you could only make playlists with all videos from the kids section, or if you add a kids video to a regular playlist, then that playlist can't be played in YT Kids. But not being able to add a kids video to my own playlist, being an adult and such, seems... incoherent.