The main aim of signing Ronaldo for Juventus was clearly to win the Champions league, which they didn’t achieve. I see this as the main reason why people claim Ronaldo wasn’t a good signing for Juventus. As well as him being one of the main reasons for Juventus’ economic issues.
The thing is if you look at Madrid’s history of contracts, RMA always awards 1 year contracts to aging players, see Ramos, CR7 himself and now Modric, they are extending the contract by one year but not more than that and CR7 didn’t like that, so he left.