Something I have recently noticed with Plasma is that the error encountered icons are inconsistent in the system tray.

For instance, battery vs notifications. Battery's icon has an icon for no batteries found, perfectly looking like an ERROR icon. This is IMHO a good design choice as it sort of conveys the fact that there's an error finding any batteries. Obviously I'd want a thunderbolt or brightness icon to used instead for battery-less Power and Brightness Plasmoids given it's also a Brightness and Energy Management controls area as well as battery status, but still.

Compare this with Notification's "Notifications Service not available" icon. That icon just uses the "Do Not Disturb On" icon. Ideally this should instead use the default notifications icon but also have the mini error icon from the no batteries found battery icon on it to convey it's encountered an ERROR.

I'd also, if possible, also appreciate Network having an ERROR icon for it too if no methods (no wireless and wired) of network connection are found that is different to the 'not connected to a network' icon (kinda like Windows did before 10... if not maybe copy Windows 10's idea of having a generic internet icon, behind said error icon, for that no network connections found error icon too for beginner-friendliness). That would help out with the consistency of error icons in the tray too.

Those aside, that is all I can think of for now, but if anyone can think of any other cases in the system tray, it'd be great to also fix those too if necessary for the consistency goal.