This has been reduced by about 60%.
He starts out season 2, now a knight, but also a false hero who has taken down Moldaver. Only he knows that he never did. This along with him looking for purpose is what makes him more jaded this season.
They even explain a bit further how his character had arrested development and why he was seeking validation and knighthood, however that's not his character's focus this season.
The goal he was clinging onto all last season, he finally reached, but he did it in all the wrong ways and even now that he's there it's not all that he thought it was going to be.
He wants to be, but he keeps finding himself in complicated situations this season and he is taking it more seriously. Thus he is more upset about his dream being more of an asterisk, thus the added jadedness.
I think the issue is that they casted an actor who simply looks older than he is. If he genuinely looked like some young-looking actor to play an early 18, 19, or early 20s kid who is wanting to be a hero to an ideology that he bought into, but has barely any life experience nor wasteland experience, the character would come across more obviously to audiences.
Instead in season 1 you had a dude who looks just about 30 years old acting like a 13 year old.
Regardless, there have been less complaints about him this season because they massively turned down the dial on his childlike demeanor and jokes. They even gave him his own good plotline to follow along with, and kudos to them for doing this all in a way that makes sense.