Splitting - Wrong Proportion

Hi,
I tried to use this tool :
https://deftpdf.com/split-pdf-down-the-middle
on a PDF and tried to split it on the middle but it didn't cut with the right proportions.
Here, you can find the target PDF and the obtained result (link expire : 02/04/2022):
https://www.swisstransfer.com/d/7d43aab7-ce4e-424d-8680-aec8febf5a22