SSIS export to CSV Flat File Destination task, error The code page on input column is ... and is required to be

The issue is caused by a clash in code pages between 1252 (i.e. Windows-1252) in SQL Server and 65001 (i.e. UTF-8) that your CSV file is expecting.

I believe one solution to the issue would be to CAST your source columns to NVARCHAR in the initial SELECT from the database, or use a Data Conversion task to convert them to Unicode strings.

An alternative would be set the code page in the Flat File Connection Manager to 1252 ANSI - Latin.