Foundation Season 3 unveils the answer to a burning question: Why was Gaal Dornick in Cryosleep for an extended time? She wakes up from Cryosleep in Season 3 Episode 1, only to discover that the galaxy has changed entirely and that the Outer Rim is now controlled by The Foundation.
Here are details on Gaal’s Cryosleep.

Gaal’s long Cryosleep period in Foundation Season 3 Episode 2 explained
Foundation Season 3 Episode 2, titled “Shadows in the Math,” revisits 151 years ago. At the time, Gaal Dornick and Hari Seldon make a crucial decision for the future fight. They got into an agreement where they will take turns in the cryosleep. In their respective turns, they agreed to be awake for a few weeks in a year to train the Mentalists on Ignis to prepare for the upcoming confrontation with the Mule.
The duo attempted their best to develop the Second Foundation into a powerful force while they were briefly awake. The group was trained by the duo in various areas. Hari educated them on psychohistory. Meanwhile, Gaal leveraged her increasing powers to teach the group to stand tall in a fight with The Mule. This training was intended to make the Second Foundation expand across the galaxy. However, things didn’t go as planned, and Hari made a controversial decision.
He didn’t stay true to the agreement and allowed Gaal to be in Cryosleep for years. Hari made this decision as he believed that her powers are important and shouldn’t be put at risk unnecessarily. He wanted her to get a good sleep before getting into the war. During her extended sleep, he continued to train the Mentalist for the psychic warfare.
However, things changed after Gaal woke up. She saw a reshaped galaxy with an aged mentor, with whom her bond is likely to change given the breach of the agreement.
