I am using QGIS installed via the OSGeo4W bundle. Since version 3.26 I have had an issue with the MapComposer. Upon export, blending modes appear to have no effect. In this case I have a bathymetric map that I used to calculate hillshades on. I tried GDAL, SAGA Analytical hillshade, QGIS-toolbox with various options as well as duplicating the bathymetry and styling that as Hillshade instead of Singleband pseudocolour. I usually add the hillshade over the bathymetry and choose blending mode multiply to reveal the underlying layer. In the main window of QGIS and the MapComposer this works and everything looks good. Only once I export the final map as an image (.tif, .png, .jpeg, .bmp), the hillshade is exported as if I had chosen "normal" as blending mode, i.e. as a greyscale layer overtop my bathymetry.
I had hoped this would change with the next update, but updating to 3.28 has not changed anything. Re-doing the maps from scratch also did not help.
Has anybody has encountered a similar problem? How can I resolve this?
EDIT: Below are screnshots from the MapCanvas and the export.