Polygons with materials - lighting and LOD issues

Thank you very much guys for the ability to draw polygons outside of airports,
which became possible recently! I would like to use this for a larger barren
area but struggle with some barriers I met when working with the following
test sample: In the following sample I covered a larger area with the
following material from the MSFS default material lib (the same applies to
individually created materials): Name=“ConcreteBare”
Guid=“{BC96E08E-86F6-4ED7-85C9-2847BE14C27B}” SurfaceType=“CEMENT”

First problem: There are
straight lines in a north-southern direction along every 3rd LOD11 tile.
This it not related to material itself as it is not happening along all the
other seamlines (east-west and 1st and second north-south). Looking closer at
the problem it revels that polygons with no terraforming applied whatsoever
(only material textures) cause a terrain mesh gap in both positive and
negative Z directions that seem to be the cause for the seamlines seen from
the distance: Second
problem:
Lighting for polygons seems to be “off” on some way and
substantially different to that of the surrounding scenery. See the following
comparison showing the same polygons at different times of the day:
You
see textures/materials on polygons become noticeably darker than the
surrounding scenery in late/early daylight hours - making it stand out like a
sore thumb. Related to that there’s a circle of “detail overlays” (or whatever
it is) following the aircraft in multiple LOD “rings” when the sun is low:
1. Dark right under user
viewpoint. 2. More brightness a little further away 3. Back to dark again a
little further 4. And back again to more brightness in the far distance. Is
there a chance these problems can be addressed or is there something that can
be done from our side to avoid these?

Using white textures makes the problem with the tiling a bit more obvious
in the different sunlight positions (same location, just different daytimes):
Noon:

Dusk/Dawn:

Regarding the straight north-south lines following every 3rd LOD11 tile I
did some further experimenting: I have been drawing a new polygon crossing one
of these lines with the default asphalt texture and terraforming applied. Even
in this setting there’s a line visible from the distance.

When looking from nearby
there’s no step in the mesh anymore (of course - because of the terraforming)
but it shows that there is still something going on here that creates those
lines seen when moving out:
Setting…

…from 11 to 10 makes the polygon invisible after the next compile. So this
isn’t a workaround either.

Any feedback would be highly appreciated. The problem with the cutlines along
LOD9 longitude lines remains for polygons. Same as the tiling.