Hi Alexander,
I moved to new version 26.5 and here my results:
Please see:
Test data(input/output/QGIS)
5175 GeoJson GeoPackage.zip (48.3 KB)
Thanks,...GeoPackage writer and specify options var gpkgOptions = new GeoPackageOptions....CreateFromEpsg(4326), // Optional: Force geometry type to MultiPolygon...