I'm still catching up on what I missed over the last few rounds of the tournament, but I did listen to Novak's presser after the final. In fairness, he didn't say he was injured, but he heavily implied that something happened. ("I insist. No, I INSIST, I'm not going to talk about it." And he's the one who said it.) Maybe he meant merely that he lost energy, which could be age, and a consequence of having played a 5-setter v. Sinner, but he DID imply he wasn't 100%, whatever he ran up against.
But to this point, I'm going to say: As the Big 3 aged, particularly Federer, even his fans began to say, "He'll need some luck," meaning in the draw, etc. Djokovic didn't get the luck in the draw, in that he was likely going to have to face both Sinner and Alcaraz, which came to be. But he DID get some luck, which he copped to in the presser, than he had a walkover and a retirement, prior to playing Sinner. You say that that can be disruptive of rhythm, but I think you're being generous. Djokovic often doesn't even play tune-ups before Majors. He knows how to be ready. At this age, he needs more rest than rhythm, IMO.
I do think he's coming up with strategies for playing Sinner and Alcaraz, and they have done some good. I don't think Sinner ever looked like a world-beater, this tournament, tbh, what I saw. But Novak beat him, and in 5, which is impressive. And he came out playing one of the best sets of the last few years, as he rightly said, against Alcaraz. But he couldn't keep it up. I have to think this is a function of age, and maybe that's what he was alluding to.
In any case, with so many stars aligning for him, if not all, he still couldn't close the deal, at his best Major. Some folks may think this is being sour on him.
@Jelenafan seems to think it's unfair to think he's done. Well, I'll be very surprised if he wins another Major, and I've stated my reasons.