I would say that looking at the movies alone, Luke wasn’t at the level of most of the prequel Jedi even by the end of ROTJ.
I’m just bringing up G&G’s pointer.
Anyway, one could also argue Obi-Wan was old in ANH, even though Yoda and Ki-Adi Mundi were also old and yet still have decent lightsaber skills.
Obi-Wan saying “I’m getting too old for this sort of thing” when he’s not even 60 always cracks me up in retrospective, thinking about how 80-year old Dooku wiped the floor with him twice in the prequels.