Yahoo shared calendar not syncing anymore with iPhone's calendar

Hi

I use iOS calendar app for years, in sync with 3 calendars of my yahoo account: 2 of them are personal, the 3rd one is a family calendar hosted on my wife's yahoo account and shared with mine.

Since a few days the app suddenly stopped syncing with this shared calendar (although I can see it in the list), no event appears anymore on this one. Of course I tried to delete and connect again to my yahoo account in the parameters, but it does not fix the issue.

I can still see all events of this shared calendar using a web browser on my yahoo account, so this is not an issue on the sharing itself.

Very annoying. Looks like something was broken recently in the iOS app.

Any help appreciated.

[Re-Titled by Moderator]