Grass is generated by the landscape texture which has a list of potential grasses. Sometimes there are variants that are no supposed to generate grass in vanilla, like the "NoGrass" ones.
Some grass mods add grasses to those landscape textures which can cause this issue.
However, not all areas are painted with the ideal variant for various reasons. One of the reasons may be the strict limitation of different landscape textures per quad per cell which I think is 4 + default. Another reason is that a mod adds or moves things around which can give some slight oddities which is what you've observed.
There are a few grass clipping fixes around but this usually in various landscape issues ranging anywhere from rough landscape transitions to landscape tears.
With the latest version of verdant, he includes a version of the fix but since it typically loads late in the LO, landscape tears are abound and quite common.
I disagree with the inclusion of the grass fix because of the reason. I did however develop a simple script to remove all the land edits, leaving the new hand placed grasses alone. The script needs work as it was never meant to be publicly released.
However the grass clipper fix is nice when its loaded early, as if its an ESM.
EDIT: I do not think this is a good inclusion for step as I believe it adds too many grasses to the tundra and some locations look odd, even for SRLE.