Confirm the issue.
It works with Joomla Text Filter (On), and the domain 'youtube.com' added to the Sandbox Iframe Exclusions List.

Confirm the issue.
It works with Joomla Text Filter (On), and the domain 'youtube.com' added to the Sandbox Iframe Exclusions List.

the problem is coming from how we add the current site to the samdboxIframesEclusions

we should be adding the current site but instead we are replacing the tinymce defaults with the current site

Also to note: when editing the TinyMCE plugin settings it says:
Additional domain names can be added to be excluded from iframe sandboxing. The current domain and this list of common domains are excluded by default. 'youtube.com', 'youtu.be', 'vimeo.com', 'player.vimeo.com', 'dailymotion.com', 'embed.music.apple.com', 'open.spotify.com', 'giphy.com', 'dai.ly', 'codepen.io'.

This was not true. I had to make my own entries for "Sandbox Iframe Exclusions List" matching youtube.com and youtube-nocookies.com and then it worked.

That's the point of this pr. Before it then none of the named sites were allowed, they are now. Youtube-nocookies.com is not in that list

I was having trouble with youtube.com before adding it to the exclusion list.

Before or after applying this pr?

Sorry I just realised you are commenting on the issue that reports the problem and not on the pull request that fixes it

Yes, I did not review the pull request. I just happened to discover this bug today. :)

if you test #48603 then we can get it merged