Jane Foster's experience with the Aether changed her nature, meaning she was actually able to sense Thanos' snap in Avengers: Infinity War. To the delight of fans, Natalie Portman is due to reprise the role of Jane Foster in the MCU, debuting as the Mighty Thor in Thor: Love and Thunder. That raises the curious question of just what she's been doing since she was last seen in 2013's Thor: The Dark World.
A few details have been mentioned on the big screen. In Avengers: Age of Ultron, Thor revealed that Jane had become an internationally celebrated scientist, and there was talk of her getting a Nobel Prize. He and Jane then parted ways, with the God of Thunder heading off on a years-long quest for the Infinity Stones. But while Portman has been absent from the movies, Jane's story continued in an official tie-in. Brandon T. Snider's novel The Cosmic Quest Volume II: Aftermath is set some months after the events of Avengers: Infinity War and Jane is one of its key characters.
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According to Aftermath, Jane Foster was one of the few who understood what had truly happened when half the life in the universe vanished. Jane's connection with the Aether had subtly changed her, and as a result she sensed the Infinity Stones being used on a grand scale. Jane went off the grid, attempting to understand and potentially even reverse the snap. That quest ultimately took her to Tønsberg in Norway, where she worked with Erik Selvig to tap into the Waters of Sight. There, she received a vision that revealed the history of the Infinity Stones, Thanos' insane quest, and the Avengers' failure to defeat him in the Battle of Wakanda.
The Cosmic Quest Volume II: Aftermath suggests that Jane Foster has been permanently changed by her experience with the Aether, something that very well could factor into Thor 4. In the comics, the ability Jane possesses is known as "Cosmic Awareness," and it's usually reserved for those with the potential to become some of the most powerful beings in the universe. Noted beings with a degree of Cosmic Awareness include the likes of Adam Warlock, the Silver Surfer, Quasar, and various hosts of the Phoenix Force. This may be tied into how Jane Foster becomes the female Thor.
Marvel Studios hasn't made any official comment on whether or not Snider's book should be considered canon. For all that's the case, though, there's a strong argument that it should be. Snider consulted closely with Marvel when writing the book, and it dovetails perfectly with the post-snap world shown in Avengers: Endgame. What's more, some of the details correspond surprisingly well; for example, Selvig is shown going off the grid immediately after the snap, explaining why his face is shown among the missing in the film itself. Meanwhile, the Russo brothers had refused to say whether Jane Foster survived the snap, suggesting that there were potential spoilers. These may not have been Endgame spoilers at all, but instead referring to Marvel's Phase 4 plans, suggesting that Jane's story after the snap could be set up for Thor: Love and Thunder.