WWE is, for lack of a better term, flying by the seat of its pants right now and the COVID-19 pandemic has made long-term booking very difficult. As a result, some major changes have reportedly been made to the SummerSlam card.
According to WrestleVotes Twitter account (hit and miss, but they have shared some solid info in the past), the original plans for the event have been "torn up," and at least two big matches have either been scrapped or altered.
One of these almost certainly involved Edge, who is still recovering from surgery after suffering a torn triceps during "The Greatest Wrestling Match Ever" with Randy Orton. There's also speculation that Brock Lesnar was set to be featured, but his next appearance is now reportedly being saved a time when crowds are allowed to return to the arenas (whenever that may be).
A rumor that The Viper might end up facing Drew McIntyre for the WWE Championship in Lesnar's stead, but that obviously remains to be seen. Orton is the best heel in the company right now, so this would certainly make sense.
Be sure to tune in to Raw later tonight for the Extreme Rules go-home show to see if we get a better idea of what to expect from SummerSlam.