It's due to yourself not confirming the behavior of the utility prior to performing actions on real data.
Indeed but frankly, the UX was really weird.
When I tried to do data transfer in foreground, it prompts for overwrite / resume / no / append.
But when I put it in a queue, WinSCP put it in the background, and it overwrites without any prompt. I stupidly assume it will give prompt just like when I tried before without queue
This UX behavior is totally different from any other file transfers app (Filezilla, windows explorer, total commander, turbocopy, es file explorer) where they will asks for confirmation before doing the queue or in the middle of the queue (when it meets a file that's already exist).
Even it's help page says it have overwrite prompt
https://winscp.net/eng/docs/ui_overwrite while in the reality yes it have overwrite prompt but only for foreground transfers. Things you put into the queue goes into background transfer and it doesn't get overwrite prompt. That help page also not helpful with what will happen if you didn't tell WinSCP to overwrite or resume or anything in a transfer script? Will it silently overwrites just like it did with queue? It was not explained in the help page
Thus I put this PSA.
Anyway, it seems photorec from CGsecurity able to find parts of the file. My tablet got blue screen while recovering tho... And now the electricity is dead...