I am running it with 4k DLDSR, upscaling 1440p to 4k, with DLSS quality.
Looks great.
1080p is 1080p. You ain't gonna solve lack of pixel density. Especially with normal DSR (not DLDSR).
What I find odd is that it's mainly in the party view tab, not the cinematics and such. If it was blurry throughout the whole game I wouldn't be as bothered cause then it would be consistent.