Qt random data remnants on disk

I am hoping I post this in the correct spot, honestly I'm not sure where it'd fall but im pretty sure its a newbie question...

I am writing an app (for both linux and windows) that will allow a user to edit a binary file on a usb drive with an option to format the drive itself. So far it seems to be working and everything seems to work just fine for both OSs (formatting for Linux hasnt been fully implemented/tested yet but I have tried a few things). However, I decided to check the physical disk and the file in a hex editor to make sure everything was working as expected. In the physical disk I found a lot (a couple thousand bytes worth) of data. It doesnt seem to be in a partition table and the ASCII interpretation of it shows things like linux paths to my install and various libraries, as well as class names such as Qt_WidgetCreate (or something similar) and language pack names.

I have no idea why anything like this would be written to the actual disk or even the file, and as far as I can tell it only happens because of something on the linux side. I have zeroized and reformated the disk and dont see anything strange appear with the Windows side, but with Linux I managed to get it to show up again after running it through some tests.

some background information: I edit the bin file by opening it as a QFile and then editing it and closing. For formatting the drive in linux I am using a QProcess of a .sh which calls to mkdosfs (it doesnt format the disk exactly like I want but its just a test at the moment).
Any information or suggestions would be much appreciated and I apologize in advance if I did not post this correctly. Thanks!