Getting different error message when uploading file through cypress than manually

I was writing end to end test case for a site. In this site, user is supposed to upload python file. I want to test what happens if I rename png file with `.py extension and upload it. When I did manually, the website gave the error

ERROR: You have submitted a file factorial.py of type py but the contents are of image/png type

However, when I uploaded through cypress using cypress-file-upload plugin, it gave me following error:

ERROR: You have submitted a file factorial.py of type py but the contents are of application/octet-stream type

Why is this so? Am I missing something or am getting diffrent message because of the way the plugin uploads file in some peculiar manner? Can I imitate the manual file upload output through cypress (that is get exactly the same error of image/png type)?

Update

I also checked for the mp3 file. Manual upload was giving error:

ERROR: You have submitted a file factorial.py of type py but the contents are of audio/mpeg type

whereas cypress upload was giving same application/octet-stream type-error.