I am keen on it is a staff mistake because he thought it is a funny video but he must be approved by a higher staff in the club. Napoli social media management is bad if a single staff can make any video and release it on social media without any double check from other staffs and approval from his boss.
Even if I'm to believe it was a mistake by the club tiktok's account holder, i think the act wasn't fair for a player that helped them to win the league title last season and performed well in both champions league and domestic league competition and all they could do is troll him for an error in a penalty kick, Oshimen is very right to get sad over their account because he deserves better, because trolling him could affect his mental health and performance on the pitch.
I watched the original video on social media and felt the players sadness because no one would be happy if their team does that to them and Oshimen has every right to get mad at the club, i feel this could be one of the reason that would make him leave team next summer, well according to a news by the journalist Fabrizio Romano, Oshimens agent announced that the player wants to take legal action against Napoli.