I\'m trying to embed a youtube livestream chat onto a webpage on my website,
This appears to have to do with the introduction of this change to iframes, at least when I had this issue.
To fix this, I would suggest the use of a script like the following:
Where chat-embed-wrapper is the parent of the iframe with the id chat-embed and VIDEO_ID (in the frame.src assignment) is the id of your target video. You'll have to modify this a little for your setup, but this is the general case solution.