For KDE Plasma desktop user, there will be soon a video recording tool available out-of-the-box!
It’s “Spectacle“, the default screenshot tool, to have a Recording tab to capture full-screen, select area or app window as a video. Kinda like the screenshot/screencast function in GNOME 40+, but I don’t think it will record audio as well.
According to this blog post, the feature will be available in Spectacle 23.04 to be released 2 months later in April.
Meaning KUbuntu 23.04, Ubuntu Studio 23.04, Arch and Manjaro Linux, etc, with the latest KDE Plasma desktop will most probably ship the screenshot tool with this function.
However, user has to use Wayland session for this feature. Which is not the default session or even not pre-installed in KUbuntu and Ubuntu Studio. See this tutorial for how to switch to Wayland or run specific app as XWayland in KDE.