The television adaptation of The Umbrella Academy leaves behind a lot of detail, including a major difference in the plot of season 2. That change also removes a subplot from the comics that provides a much more believable explanation.
At The Umbrella Academy, Allison’s power gradually returns as her vocal cords heal. The process supposedly takes a year, but the show pretty much progresses to where Allison can speak again.
In the original story, The Commission blackmails Allison and Five into going on a mission and surgically repairing Allison’s throat so that she can use her power to kill the President.
The complex story behind the return of Allison’s voice in The Umbrella Academy comics far exceeds the Netflix show. The idea that Allison’s vocal cords just healed is also a bit difficult to digest.
Not only is it less credible, it removes the impact of Allison’s power loss story. The nullification of Allison’s powers, for which she has been valued throughout her life, is equated to death at The Umbrella Academy.
If Allison can’t use or rely on her powers, who is she? The idea that Allison could simply regain her voice over time lessens the impact of her trauma and sacrifice on The Umbrella Academy.