No system tray for applications in 4.16.0 ?

I just upgraded to Xrce4-4.16.0 from the FreeBSD packages.

Applications using system tray are now displayed as regular icons instead of tray icons.

Examples I spotted are 2 Qt applications: SimpleScreenRecorder (https://www.maartenbaert.be/simplescreenrecorder/) and Jamulus Server (https://jamulus.io/) 'jamulus -s' that both used SystemTray successfully in the previous Xfce4 version.

They both use the Qt class QSystemTrayIcon which doesn't seem to work in the new version of Xfce4.

I tried to search for a "SystemTray plugin" ($ pkg search xfce | grep -i tray) but no such thing seems to exist.

What is going on with SystemTray in 4.16.0?