Speculating. 2 x 3 x 3-1/2 metal box allows 8 # 12. I see 7 # 12's with a single ended feed plus 2 # 10's. Could be plastic box but don't know the fill count.
Could be a violation here depending on how many receptacles already are on this circuit. 180 va per yoke. And you might want to just add a 2 gang box next to that outlet as i see a white cord using half of the receptacle.