According to Dave Meltzer in the latest Wrestling Observer Newsletter, executives at FOX are unhappy that WWE didn't make a bigger effort to sign CM Punk to a deal. The Best in the World has a pre-existing relationship with the network after signing a deal to be part of WWE Backstage on FS1, and the network has even publicly congratulated him on his huge AEW Rampage debut.
Meltzer says FOX was "very upset" that a big-money offer wasn't made to keep Punk from going to AEW, and that's why WWE has now brought a lot of big stars to SmackDown (which has understandably frustrated the USA Network as RAW ratings continue to struggle each week).
The deal to bring Brock Lesnar back was very much a last-minute one to appease FOX as WWE "felt the need to get Lesnar and Lynch to SmackDown right away." He adds: "The situation with FOX and WWE is always up and down with the key being that FOX’s SmackDown is used to promote Peacock, the streaming service of NBCU, particularly since FOX has its own streaming services they are rolling out."
With timing on his side, Lesnar was able to secure an even better deal than expected, and his return wasn't originally supposed to happen this soon. It's thought Lesnar vs. Reigns was being saved for next year's WrestleMania if Dwayne "The Rock" Johnson was unable to return, but the match has clearly been brought forward (a likely destination could be in Saudi Arabia next month).
We'll be sure to keep you guys in the loop as we learn more.