TYPO3 Core

In #78053 a change was introduced in the YouTubeRenderer to always add a playlist if the "loop" option is set.
The reason was, that the playlist parameter was required by YouTube but this is not true actually. It was only required for the deprecated AS3 Flash player.

See https://developers.google.com/youtube/player_parameters#loop

Note: This parameter has limited support in the AS3 player and in IFrame embeds, which could load either the AS3 or HTML5 player. Currently, the loop parameter only works in the AS3 player when used in conjunction with the playlist parameter. To loop a single video, set the loop parameter value to 1 and set the playlist parameter value to the same video ID already specified in the Player API URL:

The playlist param must not be set automatically as it does add a playlist to the video which contains the same video 2 times and does not really look good.

With playlist

without playlist