We have a point layer that we publish as a feature service via ArcGIS Pro. The points are symbolized with PictureMarkerSymbols that are 28px x 28px png images. When symbolizing in ArcGIS Pro, these symbols are not scaled. However, the resulting feature service base64 encodes the symbols with a size of 33.33px x 33.33px. The additional 5.88p pixels surrounding each image are transparent. See size-comparison.png attachment.
This feature layer is also being used in a custom JSAPI 3x application. The layer is assigned a renderer using PictureMarkerSymbols which reference the same 28 x 28 images. The symbols on the map maintain their native height and width. Also note they do not get base64 encoded.
Feature services are not honoring symbol (image) sizes authored with ArcGIS Pro and should be consistent with the JSAPI. This causes two undesired behaviors in applications:
1. The added transparency area triggers click events. For instance, popups will show when users click these extra transparency areas. From a user perspective, they didn't click the actual point.
2. The extra transparency area causes more issues when you have stacked points, or multiple points at the exact same location. When clicking on the added transparency areas for stacked points, only 1 result shows in the popup.
Refer to stacked-point-single-result.png and stacked-point-desired-result.png.