Inconsistent color markers
Gnome Calendar offers a set of colors to mark events in it, whereas the To-Do app offers a set with a more limited number of colors for its reminders (which, btw, could be reminders of events), and whereas Nautilus offers no set of colors to mark files/documents.
Expected behavior : all apps, in particular Gnome Calendar, To-Do, Files and (why not?) Photos should all consistently provide color markers and offer to the user the same set of colors for markers. I would suggest an harmonious set of colors, consistent with the colors used in some of the newly designed App icons (i.e. Photos) and limited in its number (there’s no need to overwhelm the user with numerous color choices as there’s also no need to present the user with dark-or-no-contrasting-colors to mark elements).
I should precise, regarding Files, that MacOS, DeepinOS and even ElementaryOS offer a set of colors to mark files/documents within their Files manager.
May be related to issue 817.