“Invalid_Field:Failed to deserialize field at col 0” Exception.

Set Date and Date/Time field values based on the running user locale. Check the following article for reference.
https://help.salesforce.com/s/articleView?id=000318296&type=1

 

Follow these steps to resolve this issue:

1. Find the user account which is used to insert or update data.

 

2. Find the Locale of the running user from 1.

 

3.  Check the following article for Date and Date/Time format based on the Locale and update the import file accordingly.
https://help.salesforce.com/s/articleView?id=sf.admin_supported_date_time_format.htm&type=5