“Smug celebration” refers to a self-satisfied or overly proud kind of celebration. Some synonyms for this could be “arrogant jubilation” and “conceited revelry”.
“Arrogant jubilation” combines the sense of arrogance with the feeling of celebration. For instance, “His arrogant jubilation after winning the game was off-putting to many.” Here, the term shows a celebration that is accompanied by an overbearing sense of superiority.
“Conceited revelry” implies a celebration that is marked by excessive pride and self-conceit. “The team’s conceited revelry after their victory showed a lack of humility.” This synonym emphasizes the idea of reveling in one’s success in an overly proud way.