I am using World Composition, 11x11 tiles of 2017x2017, World Origin Rebasing enabled. Using a simple material on landscape (though using tri-planar for the UVs), the farther the tile is away from the origin (0,0) of the world, the worse texture filtering is getting (textures become lowres and pixelated). Using the same material for the closest and farthest tiles from the origin, the one closest as a clean texture, the one farthest as a pixelated one (both when looked at close).
Note my material is using Absolute World Position and VertexNormalVS for the tri-planar UV mapping. It may be these nodes have limitations regarding world size. If instead I use LandscapeLayerCoordinate (so no tri-planar), I don’t have the problem.
I think this is a bug, please provide feedback, I will log a bug if this is indeed one.