It’s been 20 years since Shenmue was first released, and for all the millions of times it’s been played and completed in that time, it’s taken until 2019 for somebody to find that there’s a homage to Street Fighter hidden in the game’s code.
So yeah, it’s basically a dragon punch from Street Fighter, intended as a homage to the series by Shenmue’s developers. But while it was animated and included on Shenmue’s disc, it never made its way into the actual game.
The attack wasn’t hidden in a way that it was supposed to be found by the average player; it took some tweaks to the game’s code to unlock it. And it’s not like players have been searching for this stuff for 20 years, either; they were only tipped off in 2018 when this Japanese report hinted at this (and other) secrets tucked away unfound on the disc.