You're probably noticing what happens when a show gets greenlit for a second season before the first one even finishes airing. The production committees want to capitalize on the hype, so they lock in air dates that don't leave enough time for the animation teams to actually breathe. Season 1 likely had months of pre-production and a more relaxed schedule, while season 2 got rushed into production the moment it was announced. That creates a domino effect: less time for key frame artists, more reliance on in-between frames, and character animation gets compromised to hit deadlines.
Budget doesn't always shrink, but it gets spread differently. Studios sometimes front-load resources into early episodes to hook viewers, then dial things back for the middle stretch knowing the core audience will stick around. It's frustrating strategy, but it happens. The fight choreography probably suffered most because dynamic action scenes require way more labor than dialogue-heavy moments.
Here's something people don't usually mention: if you watch season 2 again at 1.25x speed on your player, the animation actually feels snappier and less like it's dragging between frames. Sounds weird, but it genuinely helps mask some of the quality dips because your brain perceives the movement as more fluid. It's not a fix for the actual problem, just a workaround that makes rewatching more bearable while you wait to see if they pull it back together for whatever comes next.