Muddy Poppins YouTube Video's

"To comply with the Children’s Online Privacy Protection Act (COPPA) and other laws, certain features may be restricted or turned off on content that’s set as made for kids. At the video level, these features include: 

• Autoplay on home
  
• Cards or end screens
  
• Channel branding watermark
  
• Channel Memberships 
  
• Comments
  
• Donate button 
  
• Likes and dislikes on YouTube Music
  
• Live chat or live chat donations
  
• Merchandise and ticketing
  
• Notifications
  
• Personalized advertising
  
• Playback in the Miniplayer
  
• Super Chat or Super Stickers
  
• Save to playlist * and Save to watch later
  

At the channel level, these features include: 

• Channel Memberships 
  
• Notifications
  
• Posts
  
• Stories
  

Source: https://support.google.com/youtube/answer/9632097

That's right; ALL those basic features are disabled when a video or channel is "kidded" (not a word, but that's how I refer to it).

* "Kidded" videos can still be added to playlists created by the submitter, even if the channel is "kidded". It only means other users can't add such videos to their own playlists.