This may or may not solve your problem, but either way it's worth trying. Microsoft recently changed to modern document libraries, which may have changed the behavior of your cvs-file.
In your tenant admin site, go to settings > organization and turn off modern document libraries, which will switch back to "classic" document ment libraries. You can also, in the library itself, switch to classic mode, but it would probably not affect your Linux server script.
If this doesn't work you can try to switch on OpenInClient feature which is a site collection feature in site settings.
I know these suggestions are long shots, but it gives you something to work with.