Hi Alexander,
I moved to new version 26.5 and here my results:
Please see:
Comparison(left-Csv, right-GeoPackage)
image.png (170.3 KB)
Test data(input/output/QGIS)
5330-Csv-GeoPacakge.zip (35.3 KB)
Thanks,...the default layer name, compression, etc. here }; table.Save("output...