Hi Vincent and welcome to the forum.
It seems that there must be a bug in iPhone Safari as I believe you are describing the same behaviour as in Issues with Mobile Viewing on Iphone I’ll check what is happening, possibly it’s related to a new iOS update.
What is exactly the mobile UI related issue you are experiencing? The autoplay click problem is one, but are there any other errors?
Also, if you are interested you can directly insert videos using the following trick: https://maphub.net/hyperknot/video-embed
You need to put this in the description field.
{iframe src="https://www.youtube.com/embed/z7VYVjR_nwE"}