Eh, what?
One thing to watch out for is file encoding. Our servers, file managers, etc. assume that all files are UTF-8 encoded. Especially if you’re on Windows and/or the file is in a language that contains many non-latin characters, you have to make sure the file encoding is correct.
Or someone is hijacking your FTP connection and corrupting the data, of course. Which is a plausible risk if you disable TLS for FTP.