My images are the same material, only Raster vs Ray Traced translucency has changed. This issue has occurred in all engine versions with Ray Tracing, here it is in 4.25. The material is the new Thin Translucency shader, but the issue happens in all translucent material types. Its important for me to be able to get a sharp edge on an object in the foreground when blurring the background for things like car windscreens and glass roofs.