They started when Taylor and Jack Antonoff were retroactively credited on Olivia's songs "1 step forward, 3 steps back" and "deja vu" — which were inspired by Taylor's songs "New Year's Day" and "Cruel Summer."
Olivia then released "Vampire," which included lyrics that people thought were about Taylor. When Olivia was asked about that, she didn't outright deny it, causing the feud rumors to only grow.