.desktop launcher files don't launch in normal folders

[mahesh]

Hi, I'm on Ubuntu 22.04, GNOME 42.9.
I have been able to get .desktop launchers to work, for example using the "Menu editor" program or by creating one my own and installing it in /usr/share/applications/ with the command
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desktop-file-install myprogram.desktop. In just one instance I have been able to copy one of these files into a normal folder and make it work, tough I don't remember exactly how. In no easy way I can get one of those launchers to work fine from a normal folder, despite allowing launch and despite the correct read/write permissions. I don't understand why. The files are identical, permissions and metadata also seem to be identical to me.
Someone knows where is the data that discriminates between the two files, those that launch and those that don't?
Thanks