The Umbrella Academy season 3 made a huge reveal about Five’s (Aidan Gallagher) connection to The Commission, and this made way for a theory about how this organization’s briefcases actually work. The Umbrella Academy has seen the Hargreeves go through a bunch of problems since season 1, each time triggered by an apocalypse, and as they attempted to prevent each end of the world, they learned more about themselves, their pasts, their father Reginald Hargreeves (Colm Feore), and their enemies, among them The Commission.
Because the end of the world and their troubled pasts weren’t enough, the first two seasons of The Umbrella Academy saw the title team (though mostly Five) dealing with The Commission and its agents, who were going after Five after he dropped out and finally returned to his timeline. The Commission is an organization that oversees and manages the space-time continuum, and as such, it makes sure that all events happen the way they are supposed to. The Umbrella Academy season 3 revealed that a version of Five from another timeline is the real founder of The Commission, which could also explain how the briefcases they use actually work.
Umbrella Academy Theory: The Commission Uses Five’s Power To Travel

The Commission’s engineers might have found a way to take some of Five’s powers and put them into the briefcases, but that might have also had debilitating consequences for Five. When young Five found his old self, the latter was in critical condition, which might be the result of having his power drained from him to create more briefcases. The theory can also explain why Five and Lila (Ritu Arya) were able to create the exact energy needed to power a briefcase when it stopped working, because that’s its original source.
How Do Five’s Powers Work In The Umbrella Academy?

Whenever Five jumps from one place to another, he opens a portal that, depending on the energy used by him, sometimes emits blue and white energy. Five has channeled big amounts of energy at different points in The Umbrella Academy, such as when he returned to his timeline, when he took his brothers with him during the apocalypse in season 1, and in the above-mentioned scene with Lila, and this energy manifested as bright, blue light. These visual representations of Five’s powers in The Umbrella Academy are the biggest detail to support the theory of The Commission’s briefcases using his powers, meaning that the series hinted at the big twist about The Commission’s founder since season 1.
What This Theory Means For The Umbrella Academy Season 4

A version of Five being the founder of The Commission was one of the many twists and reveals in The Umbrella Academy season 3, but unfortunately, it’s one that was ignored for the rest of the season. The Umbrella Academy is coming back for one final season, and it already has a lot to solve and address, including the rest of the history of The Commission and exactly how and why older Five created this organization. Now, supposing The Commission exists again in the current timeline of The Umbrella Academy, and Five has access to one of the briefcases, he could regain his powers and help undo the mess that Reginald unleashed at the end of season 3, helping his siblings regain their powers as well.