He was hidden when the Empire Order 66'd the Jedi in Revenge of the Sith - but by who?! He's hidden his powers to stay off the Empire's radar over the years - we know from Rebels that Inquisitors hunted Force sensitive beings for Emperor Palpatine and Darth Vader. Ahsoka reveals that Grogu was raised in the Jedi Temple on Coruscant, and received training from many masters.