Reprojection: no difference nearest vs bicubic

Dear forum members,

I reprojected a Sentinel-3 OLCI image to the standard EPSG:32631 (31N) crs with ‘nearest’ and ‘bicubic’ interpolation. The results were identical.
Later I added orthorectification and again got the same result.

What do I do wrong?

reproject_question.xml (2.9 KB)