Don’t see it as fitness, his form tends to dip that last third of the season or certainly has last two years
Probably because he wasn't properly rotated and rested.
Rodri lost form in the final weeks of the 20/21 season and didn't play in the CL final too. Some were arguing last summer that Rodri wasn't good enough to start for us. (Imagine that.) But Pep rotated him more often in 21/22 and Rodri finished the season as one of our best players.
Pep couldn't rotate Cancelo as much as Rodri, for Walker and Stones had injuries, and Walker missed 3 CL knock-out games for a stupid foul. Is it Cancelo's fault that his form dipped, given that he played much more minutes than Walker, Stones and Dias? Most probably not.