Never heard of these jails, like bubblejail? Its available on Linux too.
I know the question is vague and highly dependend on Threat model etc. Pre-enabled services, distribution adding stuff to it, SELinux confined user (not working with Plasma at all), xwayland support for keylogging chosen keys (Plasma).
Also GTK is widely used for rust apps, this doesnt exist on Plasma at all, not a problem though as Plasma is not Gnome and simply supports GTK normally.