Faulty geometries (examples for ocean, water polygons, landcover) with openmaptiles configuration

[GSYM18]

Hi everybody,
we are using Tilemaker to create vector tiles and came upon some issues with, amongst others,
the tiles containg water polygons for the Kaptai Lake (https://nominatim.openstreetmap.org/ui/details.html?osmtype=R&osmid=1626722&class=water).
To see if the issues are caused by our configurations, we used the provided default files for OMT (process-openmaptiles.lua and config-openmaptiles.json + shapefiles)
and created the tiles for Bangladesh.
However, there are also faulty geometries created that can be found in the following tiles:
Faulty ocean geometries:
3/5/3
4/11/7
5/23/14
7/95/56

Faulty water geometries:
Kaptai Lake: in zoom levels 6, 8 and from 12, the lake seems to be fine,
but in zoom levels 7 (7/96/55), 9 (9/387/222), 10 (10/774/445), 11 (11/1548/891) the geometries are faulty.

When briefly reviewing the OMT vector tiles for Europe, we also found the following "issues":
Greece: tile 8/147/99, as well as faulty landcover geometry:
In zoom level 9 and from 11 the geometry is fine, but in zoom level 10 (tile: 10/588/385) a small part is "missing".

We could also confirm the "issues" described in #847, but since there is also an open issue for this, we won't include further examples here.

Does anybody know how we could improve the above described geometry issues?

Thanks for the support in advance :)

Kaptai Lake:

Greece: