You’re kinda hopping over the point though as they continued to get shitter even after he left, once not even qualifying for the CL.
So he clearly wasn’t the issue, the entire rebuild that started with Ronaldo, Cancelo, Bonucci, then continued with De Ligt, Kulusevski, Danilo, Romero, Melo, Morata was a huge failure. They spent over 400m after Ronaldo and got worse, and after he left they got worse still.
To pin their decline on Ronaldo is ridiculous really, especially when they signed 9 other first team players in his time there.