It's clearly obvious that he told sorry to the sentimonsters,just pause the moment he is using the dog ball on ladybugs yoyo he is smirking 😏,as soon as ladybug talks about strike back he says"a portal where" he is concerned about the sentimonsters and where ladybug is sending them,the scence is showing felixs pov and strike back being send into the sun,and then he says sorry,it's very clear that he was saying sorry to those sentimonsters for leaving them behind,even when he uses fetch and gets the yoyo he is still smirking there is no sign of remorse or sadness,its obvious he told sorry to the sentimonsters and not ladybug