It does look like he is mocking him and I've only seen this now so a bit surprising he did this but like i've said he needs to focus on himself. Whatever issues his opponents are having has nothing to do with him. This goes for all other players. As soon as they see their opponent having physical issues they think they can relax and drops their intensity and start thinking of other stuff rather than trying to focus on what they have to do. Alcaraz knows better himself that he lost to the better player on the day, Djokovic really was that much better after set 1 in almost every aspect of the the game, especially serve and return he knocked him out the park.
This stuff with players getting angry at their opponents cause they aren’t folding when they show signs of physical issues is just pathetic.
Djokovic would never in a million years let that kind of stuff affect him.