Kooha is a GTK-based screen recorder for Linux for recording screens and audio from your desktop or microphone. It is very simple to use

Install flathub from the Ubuntu software repository:

$ sudo apt install flatpak from the repository:

Install Koohu from the command line:

$ flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
$ flatpak install flathub io.github.seadve.Kooha

You should now see an icon for Kooha in you GNOME applications window.