Bro, season one was peak. Season 2 was good. Season 3 is ass. Season 4 is cooked.

Fr. The animators decided to take the days off

Season 1. That had the general premise of the show and Saitama one-shotting enemies including two arc antagonists and the other's strongest monster serving as final boss. Based on the summary I read, Season 2 doesn't have any of that, unless it's in the background, and main villain's arc lasts into Season 3.

I feel like season 2 is there to establish the threat. Suiryu was a strong guy, super strong in fact. The idea that these monsters could just 'make more' is equally suprising and terrifying.

When will Saitama start one-shotting enemies again? Is he so bored of it he quit, or what?

I mean, he's surrounded by S-Class heroes most the time. They always want to fight, so Saitama just gets sidelined by societal normality lol.

I know of course it'd be over too fast if he started fighting, but what was wrong with Season 1's format of three-episode arc antagonists? That's what made One Punch Man so unique, and it was one of the very few popular 2010's animes that killed its villains, except Genus who wasn't a fighter if I recall, and reformed after his strongest monster was killed.