Calendar and iCloud Storage Issue

This question was never really answered so I am asking again:

In Calendar, an exclamation point appears beside my iCloud calendars, showing the message 'there is insufficient storage space for account iCloud'. I notice this is only happening when I receive a emailed calendar invitation from my company that is sent to many meeting attendees +-100 people and also includes a link to a Microsoft Teams meeting. When I check my iCloud storage I have 1.38TB of my 2TB family plan available. When this meeting is over and I delete the reminder the ! goes away shortly after.

I know the invitation was created on a Windows system and there are no attachments in the invitation