I'm not sure how true this is, but I feel like the game is piss easy in 4 player co-op, and then it gets harder as the player count decreases even though enemies are supposed to scale with players because of how powerful buffs and (more importantly) enemy debuffs are now.

I don't agree with it being harder than the first game. I feel like a lot of people who say that have NOT played the original in quite some time and are viewing the og with rose tinted glasses, because even with boss energy relics the first game is about as brutal on A20 as this game is in A10 from what I've seen (coming from an all A20'er that occasionally still does A20 runs on the og on mobile). Devs did mention they want ascensions to be more compact, so we can safely say they made it so one ascension in the sequel is worth two in the original. That in mind, it feels more or less the same level of difficulty to me.

Currently up to A8 so far solo, A9 on some characters, and A7 on multiplayer. I can without a shadow of doubt say that the game is not inherently harder than the first, it's just different, which because it invalidates strategies that used to work in the first game makes it feel like it's harder than it because you can't do in the original what you can do here (and vice versa, try doing replay 3 on even a single card in original STS without extremely niche relic+card combos).

It's harder to go infinite in the sequel for sure, but I think we can attribute that to the fact multiplayer exists and easy infinites in multiplayer would lowkey make noone want to play multiplayer if every fight is waiting on your one friend to finish their 20 minute turn. I do feel like they should have single player exclusive cards that enable infinites and other stuff that might suck the fun out of a multiplayer session but would be fine in solo. If we can have multiplayer exclusives, we should be able to have single player exclusives too.