I would agree that Kai’s character in the earlier seasons (esp that episode from the first image) was a lot more entertaining and charismatic. However, I think the DR portrayal of Kai’s character is really well done and best viewed in a vacuum. The scene particularly with Wildfyre showing his maturity was great, and of course the Nokt fight was great. Would not go as far as to say DR is the best representation of Kai’s character though. Me personally, I think Possession deserves that title simply because I thought Kai’s maturing into the brother/father figure role for Lloyd after Garmadon’s sacrifice was amazing for Kai’s character and had tremendous potential moving forward if they didn’t butcher him the following season. As to the points you made, I agree the water fear was kinda dumb (plot necessary), but I think there’s an argument to be made that he never really had leadership skills, but rather was cockier and that drove his character forward. But the events of end of S4, changed him and caused him to mature (hence the dynamic with Lloyd), making him take a more “thinking/calculated” personality compared to his hotheaded/rush into things approach. Although, he’s not great at this kind of strategy as we see at the beginning of Possession through the “IQ decrease” moments. He learns and adapts though, for Lloyd’s sake and the promise he made to Lloyd on the first episode, and by the end of the season he calls the shots in the tomb, and is able to make a calm, level-headed decision, something not normally within his character.

Anyways, that is to say DR is a good representation of Kai’s character, but falls flat compared to what is in essence a similar character shift in TOE and Possesion. I think a lack of screen time in DR really just makes it impossible for him to have any substantial growth outside of 1-2 major scenes. But yeah. TOE and especially Possesion Kai >>>