@Alihan: Thanks for your post. Do you mean that you had something after the !.!? What was it? Do you know how it got there?

Hey Martin, you can delete after this part.

@Marymiu: I'm glad that you have resolved it, but I cannot imagine how WinSCP reinstall can help. It's rather just a coincidence.
If the problem ever comes back, please let us know and we will try to find out the root cause.

Reinstall WinSCP helped

Hello! I am not an author, but I have the same problem. The editor is reinstalled, all the default settings, no extensions are worth it.

Can your post a screenshot of your external editor configuration?
How exactly do you open/edit the file in WinSCP?

So I just redownloaded winSCP for the first time in a while, and I remember this happening last time I used it too, where when I open a file using an external editor, I've tried using both Visual Studio Code and Sublime Text 3, they both open the file I intend to open, but they also open a blank "VS" and "Code" file that says it needs to be saved.