The resource could not be loaded because the App Transport Security Policy requires the use of a secure connection – iOS YouTube
If you attempted to click a URL within the YouTube iOS app or YouTube Studio iOS app, you may receive a message and the link does not load.
The latest version of iOS requires URL’s inside any app to use HTTPS– so the link you are clicking is likely using HTTP instead of HTTPS or the app is not binding the correct application protocol (HTTPS) to the website link. This is an issue within the app with how Transport Security was established.
The only work around is to copy the link from the app to a browser and access it that way.
For more information read this Stack Overflow article.