Invisible cfg files - why and how?

Question

File managers

Hi everyone! I saved, therefore, the Hikvision IP camera config to a folder with its own firmware in order to set up 100,500 cameras at once in 15 minutes. I set everything up fine and decided to send the config to the cloud so that it was always at hand, but ... here's a surprise: when I open a folder from IE via the config upload form to the camera, the file is there, but in this folder using Explorer and other file managers IT IS NOT !!! The display of TOTAL is enabled in the folder options. Attaching photo. Out of some sort of fright, I have cfg files assigned to the "Windows Shell Shared Library" application. I repeat: even txt and in the properties of the notepad application - the file does not appear in the explorer - only when downloaded from the webmord of any device via IE.
Whatever I do with this file (change the name, extension...) - IT IS NOT VISIBLE! Even antivirus scanning in administrator mode sees only one file in this folder... what a heresy...