im on 5.3 so yeah… :-/
try r.vt.poolscalesize X. This can help with the residency pools. Pretty sure they are there in 4.27, the RVT is like an object-pool but for tiles off the shader-sink. that command should increase the size of the pool and IF is the issue you should see immediate effect.
What I can suggest (from experience) is that if you are getting blurry-tiles of any kind in the VT-world, it’s owing to lack of a pool or buffer somewhere. The issue is having to swap in/out tiles you are looking at, but as there is not enough space, stuff just goes in then leaves, or is pushed to a higher-mip owing to lack of resources.