No data or personal information is collected by Daybar or any of the other apps on Menubar.club.
Daybar asks you to connect with your Google Sign-In so it can read and display events from your Google Calendar in the app. This information doesn't leave your computer and isn't sent anywhere.
Daybar and other Menubar.club apps are open-source, free software licensed under the MIT License. If you have any questions about Daybar or suggestions, please create an issue on Github.