Hi Alexander,
I moved to new version 26.5 and here my results:
Please see:
Test data(input/output/QGIS)
shapeFile8.7z (7.5 MB)
Please make conversion in your side from ShapeFile to Kml and test it in your side in …...Conversion succeeded, output file size is too big to open in QGIS...input ? Open also in QGIS: Convert from Shapefile to Kmz , output...