This still happens in the latest version. It's very irritating, since the screenshot command is otherwise the best way of getting screenshots at full render resolution (e.g. getting 4k screenshots by running at 200% render scale) - most other methods just capture at screen resolution.

This problem also affects the use of BIS_fnc_exportEditorPreviews, the resulting images are very lightened. As we can see, the BI author who makes Editor Previews for vanilla assets has no such problems. Can he please share a secret so that we don't have to keep using batch proces in photoshop to correct images?