Niantic has recently confirmed the new Throwback Challenge 2020: Kanto. It seems that its research was not supposed to be released just yet. It was given to played earlier than it should have originally.
The developers of the game did not say anything about how this early access happened, but it is clear that anyone who already started the Field Research Tasks can complete them, and can try to catch MewTwo.
The Throwback Challenge 2020: Kanto is a nine-part Field Research, which allows players to find rare Pokémon from Kanto. You can catch various Pokémon, such as Lapras, Nidoking, Dratini, and Aerodactyl.
Niantic has managed to disable the research temporarily before they put it online for those players who already had access to it. we have no clear date of when the Throwback Challenge 2020: Kanto was supposed to go live, but it seems that developers will not change their initial plans of launching it.
Niantic stated: “Trainers, research was released to some Trainers ahead of schedule, The event details will be released in the near future, meanwhile Trainers who received this research can complete it now but won’t receive it again. Sorry for the confusion!”
Those who have or are still working on completing the research will be able to finish it, but after the Throwback Challenge is officially launched for the public, you will not be able to complete it again.
If you got access to the challenge event early and you do not want to take part in the research now, you can wait until it launches for the public. According to some sources, the event will be out soon, and it will end on the 7th of May.