To be fair, I think the problem with Kuvira and extension both Season 1 and Season 4, is that...you got the feeling of. Wait, that's it? Despite both trying to build to something, it felt really odd and had pacing issues.
Even if Season 2 is the worst, it was less due to pacing and more the fact everyone was acting like idiots, despite some odd story choices and a laughably bad fight at the end. It was still big and grand.
Season 4... it just kind of stops, even though the last season of Last Airbender had unanswered questions. We still got to see the team enjoy one another one last time before the final credits rolled.
Season 4 ending felt like an Epilogue to an RPG where you get to talk to each of your party members one last time. It doesn't help character like Wu got some of the screen time.