Just mark it not for children. No reason not to.
You mark it here:
That's not new, it's just weird that video is flagged for kids.
Videos flagged for kids can't be added to playlists and turn off autoplay.
But why wouldn't you want kid videos on a playlist if you have kids?Because YouTube as a whole is incapable of thinking about their design paradigms for more than thirty seconds.
Just mark it not for children. No reason not to.This is what I do for my videos, but then Youtube automatically puts it back as made for kids and sends me an email about the update. To be fair my videos are 100% for kids but I really want to keep the comment section. They really don't like it when you manually change it back to not made for kids lol.
You mark it here:
Actually they can be added to playlists if you do so by going to the playlist and inserting the link of the video you want to include.