It's most likely the server that is renaming the file. Not WinSCP.
See Why is uploaded file not showing in a remote directory or showing with a different name?
Did you try to upload the file in WinSCP GUI? Or any other client using the same protocol? Won't you see the same behaviour?

Dear support,
The file in destination is renamed, when doing the upload using WinSCP .NET assembly. For instance, if the source file name is MyTest.csv, the file name in destination is not closely reflecting this name.
We used the following approaches but they didn't help:

1- update winScp.ini file to include:

2- Add the same logic in the code:(make the TransferResumeSupport to be 'Off')

Would you please advise,
Thanks