Setting the Class Boost is supposed to also set the Class DC to use that ability. This works fine for classes with multiple Key Ability options defined by the class, like the Champion and Monk. But the rogue sets its Key Ability to either Dex or something defined by its Racket.

In the past this has caused the issue that Pathbuilder would allow you to set any of the abilities that any rogue could get. So a Ruffian Rogue could set Intelligence as their Key Ability. This seems to have been fixed, but now your Rogue DC is based on Dexterity, regardless of what you set your Class Boost to.