I baked the normals from a sphere to a plane. If I change the view to lookdev it looks right. But if I change to rendered mode with a hdri enabled the reflection on the plane with the normal map looks stretched. do somebody know why?
It´s a UV problem. Check your plane's uVs. Should be completed. Else, enter into UV mode and edit the UVs until it covers the coordinates. Also: Good thinking, you've given me a few ideas with this. BTW: How did you get correct UV-localspace object normal ? just baked Normals?