SPOILERS for Stranger Things 3
Eleven loses her powers in Stranger Things season 3, but how did that happen? The third season of Netflix's popular series premiered last week, and after binging their way through the eight episodes, fans are already having discussions and debates about what's next for the show. This season, Stranger Things packed in a lot of surprises and ended in a manner that fundamentally changed the status quo. Jim Hopper is (presumed) dead, the Byers family moved out of Hawkins after experiencing one too many traumatic events (with Eleven in their custody), and it's revealed the Russians are interested in the upside down.
Besides relocating with a new family, the biggest change to happen to Eleven this season was losing her powers. After using them to extract a piece of the Mind Flayer from her leg in the season finale, she's unable to use them for the remainder of the episode. Even in the "three months later" epilogue, she couldn't move a stuffed animal with her mind. An optimistic Mike was convinced the powers would come back soon, but what caused Eleven to lose them in the first place?
Unfortunately, the show never gives an explicit reason for the unusual turn of events, so fans are left to their own devices to figure it out. A likely explanation is overexertion. In Stranger Things 3, Eleven used her powers frequently in attempts to locate the Flayed, read Billy's mind, and fight off the Mind Flayer on multiple occasions. Even someone as gifted as Eleven (who's still a young child) may have limits and she pushed herself too far. There's one scene where Mike voices his concerns about how extensively El is using her powers, implying that she could hurt herself. It also may not be a coincidence that her powers disappeared shortly after suffering her leg injury. Some have theorized the Mind Flayer is connected to the power loss, with that stray piece sapping El's abilities.
In-universe this matter isn't entirely clear, but in the real world, this reads as a conscious decision to help differentiate Stranger Things 3 from the previous two seasons. In the other outings, the finales came down to Eleven using her powers to ultimately save the day, so the show would run the risk of becoming repetitive and formulaic if the Duffer brothers ran that back again. Without having El as a superhero, the characters had to find another way to defeat the Mind Flayer, which made for a more exciting climax. Additionally, Eleven losing her powers connects somewhat to her personal arc in the third season, where she learns to become her own person. Millie Bobby Brown said in an interview Eleven is "powerful with or without powers," so this could be interpreted as an important step of her journey.
Fans have already pointed out that if Eleven regained her powers by the end of the season, she would have been able to lose them to locate Hopper, who seemingly died in the finale. With the tantalizing tease that the Russians have an American prisoner in the grasp, many are hoping that Hopper actually survived, but that's a mystery that won't be resolved until Stranger Things is ready to come back for season 4. It'll be interesting to see how El's powers are handled moving forward; the twist felt very random, but it's a major dangling thread that'll need to be resolved one way or another.