Day-at-a-Glance (“DAAG”) widget doesn’t clear completed TODOs.
Try this
Create a Todo. (you may have to do the rest of the steps after quitting and restarting Notes)
See the Todo in the Day at a Glance Widget (there is a calendar setting that controls whether Todos show in calendar. You may have to adjust this setting)
Double-click on the todo in the DAAG widget
Mark the entry Complete - Window closes, but DAAG still shows TODO as active
OOH… SO DOES THE Calendar
These should clear upon being marked complete. Or color change or…