AppCenter's automatic update notification doesn't work anymore for a few days caused by missing file /usr/share/applications/io.elementary.appcenter-daemon.desktop.
You are correct and I can confirm this issue. However, StackExchange is for asking questions. It would be very helpful for the elementary developers if you raised this as an issue on the AppCenter GitHub repository
If your question was how to fix this manually, you can create the
/usr/share/applications/io.elementary.appcenter-daemon.desktop with the
Exec key set to