Ok here is what Robert Garcia has to say about Joshua's breakdown:
“Joshua was mentally defeated since round ten or eleven," García told Izquierdazo. “Round ten was a big one for Usyk. That changed the whole fight, and mentally we were defeated. At that point, we were relying on a good shot or something like that, because Anthony is a hard puncher, and one shot can change a fight. That is what we were hoping for, one shot, because he (AJ) was dominated at that point of the fight."
https://www.boxingscene.com/robert-garcia-feels-joshua-mentally-defeated-tenth-usyk-rematch--168622His point is that when AJ had a very good round in round 9, but he wasn't able to finished Usyk that time with that body shot.
And then Usyk, the fighter that he is, wanted to erase round 9, simply came back in round 10 and after that, it seems that Joshua is spent already and tired and yeah maybe mentally defeated and asking how can he can't finished him in the previous round and then make a huge comeback? Questioning himself, but again, Usyk is far more superior than him so 9 out of 10 fights, Usyk will beat him.
And then Robert backtrack his statement or at least there is "lost in translation",
Robert Garcia Denies Criticizing Joshua, Claims He Was Mistranslated Garcia says his words had been misinterpreted when they were translated into English from Spanish, and that he was not trying to be critical of his charge. Garcia linked up with Joshua heading to the Uysk rematch.
“I haven’t talked to nobody, especially in English,” Garcia told ESNews. “You’re the first person I’m talking to. I talked to a Spanish reporter that I know so I gave him a little interview. But from Spanish translated to English they make it seem ‘Robert talking sh!t’ pretty much. But no. I wouldn’t say that about my fighters, man. I've never done that before and I never will.”
Just bothered me that a trainer will say that to his boxer after that fight. But let's see if he will continue to be with Joshua after this one, we have heard what Anthony said and that he will continue with his boxing career. I have a feeling that we will still be train by Robert in his next fight and then we will see if the partnership will carry on or not.