When you complete a zone/chapter, usually by defeating a big boss, the entire playground gets a “level increment”, meaning new and stronger monsters replace the ones you knew in every zone.
I think many share the experience of entering Sacrament and coming back to The Shallows only to find heavy armored Risens instead of the familiar horseshoe crabs…
This is a recurring pattern throughout the game, where it feels like you are punished for advancing the story, trapped in some kind of rat race you’re constantly losing.
And it’s a sour experience.
One of the strengths of the game is exploration, and personally, I would love to come back at an earlier zone and have my hands free to find secrets and shortcuts I missed. It is in fact the complete opposite, to the point you feel forced to go into the new zone and farm for levels and equipment upgrades before you get to enjoy the game again.
It feels artificial and unfair. I don’t think that’s the intended effect.
But if it is the intended effect, you should know the sudden bump in difficulty is extremely jarring. I used the word “trapped” earlier, and it is exactly how I felt when monsters far above my grade trounced me at a place I had just cleaned.
The game doesn’t prepare you enough for this. Talking to NPCs does give the impression the plague worsen with time and renders beasts fiercer, but perhaps a cut-scene after each zone (a dark wind sweeping across Sacra, for example) would help easing players into their new reality.
Additionally, you might want to space out the level increments a bit, maybe with a mid-boss early into the new zone as an intermediary step. Going from 12 to 14 then 16, instead of 12 to 16.
I expect a lot of players will quit over this, simply because we expect a logical progression of difficulty. A progression that makes sense, if not mechanically, at least narratively. Your current system does neither.