In the attached picture all dynamics are grouped. As you can see the decrescendo in the lowest voice is longer than the others. This is due to an option in the extended engraving options for dynamics: Hairpins that end before a note on downbeat may cross the barline.
This seems wrong. Although the hairpins in the other staffs would officially be allowed to cross the barline they actually don’t. Below the lowest voice there is no barline, so obviously Dorico allows the hairpin there to be longer.
I would expect that all hairpins should exceed the barline as they do in the lowest staff. Generally I would expect Dorico to not treat the lowest staff differently, the grouping of the dynamics should overrule the presence/absence of the barline.
When I change the setting to “do not cross barline” all hairpins end at the same horizontal position. But, of course then the crescendos that end in the first shown bar end before the barline.