Hi Alexander,
I moved to new version 26.5 and here my results:
Please see:
Comparison(left-Csv, right-Shapefile)
image.png (179.0 KB)
Test data(input/output/QGIS)
5324-Csv-Shapefile.zip (47.0 KB)
Thanks,...have X/Y, ensure they are numeric and not surrounded by quotes...either: separate X / Y columns (numeric, no quotes), or a single column...