https://www.techradar.com/news/heres-why-the-htc-u12-never-happened

“There is no ‘master U12’, the [HTC U12 Plus] is the flagship, and the next one that’s above that phone will be the 2019 product.”

That’s how Fabian Nappenbach, director of product marketing for HTC, explained the reasoning for calling this year’s phone the U12 Plus, despite there confusingly being no ‘original’ HTC U12.