Except Luke wasn’t “changed for the worse”, IMHO.
I really don’t understand what people watched (and then I’ll promise I’ll shut up. And always remember “De gustibus non disputandum est”).

Luke’s strenght was never his infallibility. Luke wasn’t Superman. Luke wasn’t a perfect hero. Never. He always made mistakes. While Leia was fighting in the Alliance, he was “playing” on Tatooine and he wanted to become a Rebel just because he wanted adventures. In Empire he makes a huge mistake that brings to him losing a hand and almost dying. In Return he almost falls to the Dark Side as soon as Vader taunts him. That’s why in my opinion TLJ’s Luke is in line with OT. What he did with Ben was a mistake, and the movie itself recognizes it as a mistake. Objection: “But he tried to redeem Vader. Why didn’t he do the same with Ben?” —> Well, of course because in this case he was responsible.
Everyone loved The Mandalorian scene because “that’s the real Luke Skywalker”. Excuse me? In Empire, Yoda says that a Jedi uses the Force “for knowledge and defence”. That’s precisely what he does in TLJ, he projects not to kill but to protect the Resistance. THAT his the concretization of Luke’s arc. His scene in The Mandalorian actually builds on TLJ’s Luke. It mirrors Rogue One’s Vader scene, and Luke (unlike Ahsoka) doesn’t have any doubts about training Grogu. Luke is hot headed, ready to do everything to rebuild the Order. What I’m saying is that there’s only ONE Luke. A flawed hero who makes mistakes (in OT, in The Mandalorian, in TLJ) but always manages to learn from those mistakes. Yet almost everyone is like “I loved him in the Mandalorian because he’s a true jedi there (even though he acts almost like a Sith). But I hate TLJ because that’s not Luke (even though he makes a mistakes, learns from it and brings his arc to a conclusion by using the Force to protect others)”.

I’m sorry for this. I’ll delete it if it’s too much, lol.