When I use the print tool in a WAB-created web application (in Portal for ArcGIS), the output comes with multiple labels for a single polygon feature. This is somehow connected with the dpi parameter since the number of labels increase with increasing dpi value. Seems like the system divides the map area into grids and each feature having a part in a specific grid is displayed with a label on that grid. The grid size is obviously defined by the dpi value but I was not able to find out the direct connection (How an A3 Map is divided in X&Y when dpi is set to 300?) It seems all right when dpi is set to 100 but what if I need some quality?
Another problem arising with increasing dpi is the legend misprint. Legend is also OK when dpi is set to 100 but the print tool fails to draw the symbols in the legend when dpi is increased.