Hi, I am using now the zipped x64 version of Inkscape 1.0. When I save a file it always try to use the normal svg format, but I usually save my files as Inkscape svgz. Inkscape does not seem to remember the last used format and I can not find an option to set the default file format for saving in Preferences either. I was investigating a bit and the "preferences.xml" in %appdata%\Roaming\Inkscape seems to store the last used format when saving for "Save As" (<group id="save_as" default="org.inkscape.output.svgz.inkscape" in my case) and for "Save Copy" (<group id="save_copy" default="org.inkscape.output.pdf.cairorenderer" in my case), but even when I use Save As and Save Copy it only remembers the last used dir, but not the file format. I think this is not related to version 1.0, since it happened since at least version .48.

As you can see in the screenshots attached, even when the file is currently saved in svgz format, it tries to use svg as file format when I open Save As.

Just checked, just in case, and it happens with the installed x64 version as well. I am using the Lation American Spanish version of Windows 10 Home, and Inkscape sets in English language.