Found the problem. From a post on github () I found that the settings for antialiasing had been depreciated.
By editing /usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.xsettings.gschema.xml and removing:
</schema>
<schema id="org.gnome.settings-daemon.plugins.xsettings.deprecated">
Then sudo glib-compile-schemas /usr/share/glib-2.0/schemas. This fixed the problem starting NanoVNA-Saver on Ubuntu 22.04.
N4RFC