I have installed gnome-shell-extension-desktop-icons 20.04.0-3~ubuntu20.04.1 from focal-proposed.
The issue is fixed now: aspect ratio of desktop thumbnails is correct.
I have installed gnome-shell- extension- desktop- icons 20.04.0- 3~ubuntu20. 04.1 from focal-proposed.
The issue is fixed now: aspect ratio of desktop thumbnails is correct.