HDRI Backdrop is blurry

Hi there,
I am having issues with a blurry hdri backdrop. I imported an HDR and set it up as cubemap for the hdri backdrop. Its says: Imported: 6080x3040 - Displayed 4096x2048x6 (Cubemap) - Max In-Game: 2048x2048x6 (Cubemap).
So the resolution is already downscaled and I have enabled the “No Mipmaps” option. It is still blurry and I can’t get it sharp. Can anybody help me with this? I am not making any progress to fix it…

Best regards
HDRI Backdrop

Screenshot

HDRI Settings