I agree that a strict reading of sections 6.2.1 and 6.2.2 would seem to imply that an EXT-X-ENDLIST tag can be added to a live playlist, but I have never seen anyone do that. For example, if we want events 6 hours long with a 30 minutes sliding window, we would like to remove some parts of the playlist. According to the standard, an HLS playlist which has EXT-X-PLAYLIST-TYPE: EVENT MUST NOT change or delete any part of the Playlist file; it MAY append lines to it. So we fall in the third case LIVE which doesn't have EXT-X-PLAYLIST-TYPE (my example) and which allows remove part of the playlist file. And as you said, it seems to be perfectly valid to have an EXT-X-ENDLIST tag at the end of it in this case. I think that the end tag is detected because playbackType property changes from LIVE to VOD, but the duration never seems to be updated. Thank you for you answer, I'll contact Apple Developer Support and I'll file a bug report if needed.

Looks similar to my bug (UIKit): https://developer.apple.com/forums/thread/729183