Ultimate team difficulty change, in game popup.

I have been getting a pop up in the top right of the screen during ultimate team weekend league and rivals online matches, saying the “difficulty has changed to world class”. On other occasions it says it has changed to other difficulty levels with the same pop up, usually after a goal. How can the AI difficulty level change when you’re supposed to be playing another player online? Surely that means the AI is determining the outcomes of your online matches? Is that legal?

I see other players of ea fc 24 have made and posted videos with same problem which gives us the visual proof that this is happening. 

What is the explanation?