Maybe Abomination Vaults and Age of Ashes are just exceptionally brutal, but when you're expected to make DCs against a 7th level challenge at 4th level, that's pretty tough. Even a simple task like high jumping onto a table during a combat is impossibly difficult using the DCs from the CRB.
... How tall are your tables? Like, by taking the Leap action you get 3' vertically and 5' horizontally with no check. Not to really defend the High Jump check in general because that DC seems unnecessarily high anyways. Then again, a situation where you
have to jump something instead of clamber onto it is such a weird corner case that I have trouble actually thinking of one at moment.
Also a 7th level challenge at 4th level would be the combat equivalent severe solo boss or extreme-level threat. Without looking at the AP, if I were using that it would be something that would tell the players they aren't able to advance this way currently unless someone was
really specialized, and even then they might well not
want to figure out what's behind that kind of check.
My experience is that it's far more common to be making checks against higher DCs than lower or at-level DCs. Like 50% are higher, 25% are lower, 25% are at-level.
Yeah, maybe it's just the APs. For me, I take a more naturalistic approach; so having a skill allows you to carry out crazier and crazier plans, rather than being hard-limited by something. For example, being a legendary climber who can nail a DC40 Athletics check to climb a castle tower directly is not something that should be required by a game, but rather an option opened up by having the skill. Instead of taking a more complicated route, that specific character can circumvent it with their amazing skills. Maybe that's the disconnect here.
But the thing is that it should be the exception. Even if 25% of checks were 3+levels over your level, it would be too much. The cost of failing (or especially crit failing) a higher level check is so much worse than what you gain by passing (or crit succeeding) an at-level or lower level check. If you crit fail a higher level DC against a big level fireball, you're taking double damage from an already more powerful spell than you should be facing at your level. The crit fail condition exacerbates that. So you have 90-point damage fireballs. You have 14 points of persistent piercing damage (which happened to my player in Abomination Vaults).
I (and I hate to say this) - I don't think Paizo understands this.
Yeah, without being able to check it, what you are describing is pretty problematic. I don't think PF2 really
requires that sort of play, and I would personally avoid it myself.