Brainwave, when you import large textures, they can sometimes have the LOD sampling set to a lower texture? EG, it’s only sampling a 2k mip vs the 8k.
Double-click your textures in the content explorer and check if they are forced to sample from a lower mip/res. Forget the setting but it’s noted in the metadata on the top right, and I think it’s a dropbox near the top of the editable settings.