The Undertaker signed a deal to make an appearance at the Starrcast 2 wrestling convention in Las Vegas on Saturday, May 25. The convention is happening the same day as AEW's Double Or Nothing event and the two events are affilated with one another. The difference is Starrcast isn't an official AEW event.
This was a big deal to Vince McMahon according to Dave Meltzer. He noted that Vince McMahon is under the impression that Starrcast and All Elite Wrestling are directly related to one another, and he's not happy with the situation.