UPD content is not amateur footage. It includes 4K HDR movies, professionally scripted web series, and documentary features produced by award-winning studios. Shows like Cobra Kai (which migrated from YouTube Red to Netflix and back) exemplify the fluid nature of UPD content.
The most likely explanation is a keyboard slip. “xxxn” could be a mistyped version of:
For desktop users, clearing your cache or simply refreshing the page usually pushes the latest UI changes.