My system tray icon for updates is gone. I don’t know when it disappeared but it was recently, and I think after an update.
In Pamac there’s a setting to hide the icon. I’ve checked it and it’s toggled off so the icon should be showing. I even tried toggling this on and off but not change.
The update icon in KDE Plasma will normally be the Octopi Notifier.
Right-click the system tray to see the options, and check whether it’s still listed among the applications and entries. If not, then you should be able to start it from the application launcher menu.
The executable is called octopi-notifier. But maybe you never had Octopi installed.
Look for pamac-tray-icon-plasma instead. If you do not have that either, then you must have uninstalled it, and in that case you can reinstall it with…
sudo pacman -S pamac-tray-icon-plasma
… or…
pamac install pamac-tray-icon-plasma
If you do have it installed, then try starting it from a terminal to see whether it throws up an error message.