Stop notifications on shared calendars

I am getting all notifications for shared calendars in my Apple Calendar app. I have tried turning on "ignore alerts" in the get info of the calendars, and I have turned off "Show shared calendars in the notification centre"

The offending calendars are only the ones that are in the same Google organisation as me.

I have tried sharing them in many different ways from Google, including delegation, manual share, and adding a colleagues calendar, all with the same result.

I get all notifications including invitations to their events, even if their calendar is hidden (not ticked on the left of apple calendar). I do not get email notifications, only notifications on the top right of my mac.

This feels like "ignore alerts" and "Show shared calendars in the notification centre" are broken. What else can I do?