Cannot un-see event in my calendar which has been deleted in a family member's shared calendar

My wife and I have shared calendars, with view but not edit permissions.

I invited my wife to a recurring event with my wife and she accepted. So I could see it each week in my calendar (in blue) and I could also see the shared entry from her calendar in green. Her availability changed and she switched from "accepted" to "declined". The events duly disappeared from her own calendar. But in my calendar, I can still see every week her green entry. I wouldn't mind if it were a one-off but this is every week.

I have tried several things to make this weekly green entry go away, all unsuccessful: closing and reopening both our calendars on our phones; and deleting my original entry for the recurring event which I had shared and putting a new recurring event in my own calendar worded slightly differently.

But in my calendar I can still every week see her green entry for the original recurring event.. an event which is no longer in her own calendar. How can I get rid of this please ?