There needs to be notifications for ANY point at the everything level where a custom field will be added to the entire workspace. Currently, if you create a calendar and then set it to view by a date CF and not the start/due date, the CF will be added throughout the workspace with NO WARNING NOTIFICATION.

Then there's no way to downgrade the CF's hierarchy so you're either stuck with dealing with an extra field everywhere it's not needed or you have to create a new field and manually transfer the data.

See also: https://clickup.canny.io/feature-requests/p/add-columns-in-everything-view-without-adding-custom-field-on-the-everything-vie