One Piano Voice is louder than all the others

Hi @boomerhead, difficult to diagnose the culprit without having the Project.

Can you upload a Dorico file? Best to cut it down to the place that has the issue.
Here more infos on how to do it (#4).

But you can try to deactivate some options in Playback Options/Dynamics in particular the ones under Humanize and Polyphonic Instruments