She mentioned Glastonbury in her BRITs speech in May 2021 so it definitely didn't drop immediately out of her conscience after Folklore/Evermore
https://www.thelineofbestfit.com/news/latest-news/read-taylor-swifts-full-brits-global-icon-award-speech
Shania Twain just said on the John Bishop Show that Glastonbury is on her bucket list and she's been asked before, but just hasn't been able to make it work yet. 2024?