- Reddit post from a GO Fest attendee has confirmed this
- People in the comments of the post corroborated the lack of shiny Abra

On June 14, 2019, Reddit user u/LNinefingers posted a thread in r/TheSilphRoad announcing that the release of shiny Abra yesterday was a glitch.
From the Reddit post:
Just confirmed at fest by a Niantic rep at the help desk tent. Said it was a glitch yesterday and is not available anymore.
Not cool, Niantic.
Other players at GO Fest arrived in the thread to confirm they haven't seen a shiny Abra in some time.
Shiny Clefairy also seemed to be a mistaken release, as confirmed by this comment by u/PhoenixFarce1978.
The shiny Pokemon confirmed to be at GO Fest was Horsea, with increased shiny spawns for other species around the city(and across the world in-game).
For more information on other mistakes Niantic has made, check out our Impactful Mistake Timeline.