With DSR what gets the grass is gaussian filter that gets applied across the whole image when rescaling. CDPR Red engine uses deferred rendering technique and does all transparent geometry in a separate pass, and somehow transparent textures don't get any post processing AA at all, but they do get DOF treatment. I suspect that's what changed with the "downgrade" - moving from forward rendering technique to deferred rendering sacrificing alpha blending in the process, and additionally somehow fucking up the separate transparency pass so it can't be picked up by post processing AA.
I did have some success in improving grass and trees by using sparse grid super sampling for transparency AA in nvidia inspector, allowing negative lod bias and setting it down to -0.5. Lower than that temporal aliasing gets noticeable. These zoomed in 1080p screenshots show the difference at 8xSGSSAA LOD bias -1.375 but the shimmering is very noticeable unless using DSR
View attachment 65072
Left: LOD Bias = -1.375; Right: 8xSGSS Transparency AA and LOD Bias = -1.375;
Currently experimenting with:
Antialiasing mode: override
Transparency supersampling: 8x Sparse Grid Supersampling
FXAA: On
Anisotropic Filtering Mode: user defined
Anisotropic Filtering: 16x
Negative LOD Bias: Allow
LOD Bias: -1.375
Texture filtering quality: High Quality
Max prerendered frames: 1
Triple buffering: On
Vsync tear control: Adaptive
Vsync: Force On (in game it's off, uncapped framerate and exclusive fullscreen mode)
You can play with ranges of 2x to 8x Sparse Grid Supersampling, and negative lod bias down to -3.0, you'll see different amounts of shimmering on the vegetation and castle walls while moving the witcher sideways (temporal aliasing) which can vary depending on screen resolution.
EDIT: I finally settled at -0.5 lod bias and 2x SGSAA for 1080p ... I feel it's most balanced for my resolution and has least shimmering ... anyways my conclusion is that most benefits of high level supersampling is lost here (nicely averaged alpha coverage samples) because after all that good work, what final shader does is simple alpha threshold test and only works with color sample. It's far from proper blending but I do feel like I'm seeing less "blobby" vegetation around if you know what I mean.