iCloud Calendar cannot be accessed by users through the existing web application within the iCloud website created by the Apple company, the problem affecting quite a large number of users around the world at the moment.
As usual, the Apple company does not list the existence of any problems with its system, so we are most likely talking about a bug that only affects the iCloud Calendar web application, because other web applications available in iCloud.com are not affected in any way.
As soon as things are back to normal I will let you know.
