
He’s been appearing on Raw for more than a month, ever since he picked up a surprising win over Seth Rollins on Saturday Night’s Main Event (you might remember that match as the start of the “Ruse of the Century” angle). His pursuit of Rollins has now landed him in a Clash in Paris 4-way for the World championship Seth now holds (via the end of the “Ruse of the Century”).
The booking of that title bout caused folks who care about WWE’s brand split to say, “WTF?” It took a week, but the company has
partially addressed the roster issue by quietly moving Knight to the Raw roster. At least on WWE.com:

At this point, there’s been no storyline justification for the move. WWE briefly had an open “transfer window” between Raw, SmackDown and NXT at the start of this year, but that shut with Royal Rumble.
Presumably, blue brand General Manager Nick Aldis is still haggling with his red brand counterpart Adam Pearce over compensation for the Megastar.