Do Spellcaster Class DCs not increase?

Question

This feels like a stupid question, but I can't find any actual answers.

While building a higher-level character to play with the system a little, I noticed what appears to be an omission. At some point in each class's progression, the Class DC will increase incrementally. For example:

Mighty Rage Barbarian lvl 11th

Your rage intensifies and lets you burst into action. Your proficiency rank for your barbarian class DC increases to expert. You gain the Mighty Rage free action.

But in the spellcasting classes, the Class DC is not explicitly mentioned in what appears to be the appropriate feats. For example:

Expert Spellcaster Wizard lvl 7th

Extended practice of the arcane has improved your capabilities. Your proficiency ranks for arcane spell attack rolls and spell DCs increase to expert.

Is this a weird omission in the actual writing? Or am I completely misunderstanding the way Class DCs work, and the spellcasting classes just use their Spell DC instead of the Class DC?

Answer 1

The latter

Spellcasters call their "class DC" "spell DC"; those two are equivalent in any way that I have seen.

I have not found any class abilities for spellcasters that call for a "class DC", so indeed, I think you have misunderstood class DC slightly.