I need to insert some text in existing PDF and found out that some paste operations are not possible. After more that 2 days of trying to find out why, by chance I saw that the text that I wanted to copy contained some unicode characters, in particular the %E2%80%8B is the code for a "ZERO-WIDTH SPACE" character

This block completely the paste operation, it would be much more useful to remove those special chars if they are not supported.