Very similar to Bug 423625. Basically people disable this icon not realizing that it'll shut down all the notification handling--because we don't tell them. See an example of this at Bug 483643. We could add some text that tells people what will happen when they do this, but I think it would be better to not let it happen in the first place, by de-coupling notification handling from the widget.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/6044