In classical chess, yes; in Blitz and Rapid he's still one of the best, but there's lots of good competition.
One of the biggest examples of this was in his title defense against Caruana. Every game of that match had been drawn, and in the final game Magnus had a very promising position where he could squeeze with basically no risk.
Instead he offered a draw which was immediately accepted. That sent the game to rapid tie breaks where he casually butchered Caruana 3-0.
And no great player is bad at any time control - they're just 'less good'. Except Magnus - since he's #1 at everything he's just more or less dominant.