I will give you other Ronaldo as other example. I am from old era, so I better know this Ronaldo.
Old Era Ronaldo wasn't so fit towards the end of his career at Real Madrid, for example. I remember he would get criticised at Real Madrid for being overweight and had poor form at times. That was between 2005 and 2007 if I recall well.
Even if you have a very good skill, if you don't have good body physique and not fit enough, it will affect the way you play especially at top level and end up warming the bench. Look at what happened to Hazard.
Really? He used to score 50-60 goals per season. Not its only around 20 (in Saudi Pro League...)
Maybe you have not been following well.
He totalled 50 goals in 2023 a few days back, doesn't seem bad to me for a 38-year-old, does it? Obviously, if you are going to base on the past tallies of goals, then you have to include other competitions too.
I think the club also matters. Manchester United really treated him so badly on his return, but you could see he saved their asses so many times.