I'm not certain yet as to whether Asobo intended for Grass to be excluded by Vegetation Exclusion Polygons.
AFAIK Grass is rendered as a function of local terrain mapped Material type / colors; it is a separate annotation routine from that of Trees.
This image is a Vegetation Exclude Polygon area in my Project that sets all sliders to (0) except Brightness at 1.0 (less=darker annotation):
Note that Grass persists like a deplorable "Grass Roots" rebellion by a Poaceaen, ubiquitous family of monocotyledons.
https://en.wikipedia.org/wiki/Poaceae
Allergenic Autogen Anomaly ?
<
Zoysia ! >
(...Gesundheit.)
en.wikipedia.org
AFAIK, it is by design in the current SDK methods, that Grass is rendered where there is various shades of Green, and less so in "Dirt" areas.
IIRC, to exclude Grass, one must use these methods:
https://www.fsdeveloper.com/forum/threads/issue-with-grass-not-the-smoking-kind.451405/post-874261
https://www.google.com/search?client=firefox-b-1-d&q=site:www.fsdeveloper.com+MSFS+Exclude+Grass+concrete
Notice the OSM Road is able to exclude the Grass even if superimposed over MSFS' default MSVE (aka "BING") photo-real imagery ground texture; notice as well that OSM Roads are "tinted" with the color of underlying MSFS default MSVE photo-real imagery ground textures:
PS: Has anyone else noticed that when MS' servers choke during DevMode, in
offline mode, land class type textures are applied to OSM roads ?
One might wonder if we can toggle the 'transparency' / 'Opacity' attribute so OSM roads have a proper road texture in
online mode ?
Regardless, IIUC, there should be no Grass popping up through OSM Roads anywhere in the MSFS world.
GaryGB