(C95) [GEGERA STANDARD (Gegera Toshikazu)] Biribiri Shichau (Toaru Kagaku no Railgun)

No one decided anything. e-hentai updated their series tags to that format a few years ago; seeing how e-hentai allows community uploads while nhentai does not, yet nhentai started using the exact same format at the exact same time, it's obvious that nhentai has an automated script running in the background that periodically rips e-hentai's new content and re-uploads it here as-is, with the actual human staff manually fixing the tags every now and then but otherwise putting precisely zero effort into procuring content (while still pocketing the ad money).

Whoever decided they should start titling everything with the | without updated everything else that's already been uploaded needs to die and burn.