I’m talking, of course, about Miraculous Ladybug PV (Promotional Video).
The Miraculous Ladybug That Never Was: Diving into the Lost “PV” Animation miraculous ladybug pv
You can find the PV easily on YouTube (search "Miraculous Ladybug Anime PV"). It’s only about two minutes long, but it has fueled fanfiction and theories for over a decade. I’m talking, of course, about Miraculous Ladybug PV