Regardless Niagara or Cascade, dynamic parameters for particles are passed to pixel shaders from vertex shaders via InterpolantsVSToPS.
It can cause a precision error on some materials, for example like the following image.
If we set the material's dynamic parameter to 1.0, you can see the particles looks noisy incoIrrectly.
Because its interpolator output values slightly different from 1.0 to each pixels. As a results, frac(dynamicparameter) of some pixels returns 0.9999 because the dynamicparamter of the pixel is less than 1.0.
I tried adding "nointerpolation" to DynamicParameters' interpolators as a test on 4.23 and it seemed to fix this issue.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-78214 in the post.