I am also looking for a bulk solution for this. It happens whether you merge or dissolve if the original shapes are not perfectly aligned. I am also going through one polygon at a time and cleaning up.
This actually worked pretty well https://pro.arcgis.com/en/pro-app/2.8/tool-reference/data-management/eliminate-polygon-part.htm I just made sure to choose area and set a small area so that it would only get rid of the extra vertices, I still needed to do some cleaning, but this helped a lot.