Swift has already teased that her new album is in the works, and her post could be a clue to the theme. Just before announcing her sixth album in 2017, Swift posted a mysterious series of snake videos on social media signaling her darker Reputation era.
On the flip side, the palm trees and stars seem to signal that Swift is taking a lighter approach for her next album. As many fans pointed out, a palm branch symbolizes "victory, triumph, peace, and eternal life." As you'll recall, Swift had the word "eternal" stitched on her dress when she attended the Billboard Music Awards in 2018.
Perhaps after "the death of her reputation," Swift is alluding that her next album will be all about her rising from the ashes and finding peace in her new self. In fact, Swift alluded to the palm trees quite a few times during her Reputation era, including her outfit in her "Look What You Made Me Do" music video, her "End Game" music video, and her artwork for Reputation.