I was mistaken and said KDE rather than GTK theme but you just need to add this add an environment variable before the operator on the desktop shortcut file and it should work
_JAVA_OPTIONS="-Dawt.useSystemAAFontSettings=on -Dswing.aatext=true -Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel -Dswing.crossplatformlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel ${_JAVA_OPTIONS}"
Oh its one of those Thinkpads that isn’t actually a Thinkpad like the Thinkpad Yogas. My ideal Thinkpad would be a proper release of the T480 25th Anniversary Edition with newer components.