Several have been. There's the easy answer with Bret Hart. Brock Lesnar left twice when he was on top. Before jumping to TNA in '08 Jeff Hardy was a multi-time world champ who last fought Punk for the gold. Hogan had world title matches with Yokozuna before heading over to NJPW and then WCW. Probably a few others Vince pissed off were granted their release around that time too. There are also companies outside of WWE like ROH who have released such people.
I get choosing Bray here, but I do not gel with the notion that an announcement in wrestling makes it less of a surprise, or some mark against it. The sport is riddled with spoilers. I'd argue wrestling thrives on being heavy-handed. Punk showing up as promoted was refreshing to me compared to AEW's usual surprise appearances. For that I think Punk debuting instead of some MJF trolling is the surprise of the year.
There was also Punk telling the crowd Daniel Bryan, another released multi-time world champ still in the WWE main event scene, was on his way made it a two-fold surprise.