iCloud Calendar (caldav) not syncing with Icloud calendar

Does anybody know how to get the URL for iCloud caldav ? I tried more than 10 URLs , even tried exampled searched in Google how to get the correct URL , but nope. Does anybody has the same problem ? There is always a red triangle after some seconds when trying to sync. The strange thing is that everything works fine on my iPhone and even my contacts are syning fine with iCloud. I think the problem started when Apple launced the 2 factor system . I even have a 2 factor App specific pasword . I have the impression that Apple wants us to use Apple mail clients

https://caldav.icloud.com/.well-known/caldav

And you need to create and use an app password, not the account password.

This will setup correctly if you add the account in Menu > Accounts > Add Account > Calendar > iCloud Calendar.

I did this but nope, you can see the error log here what I get : I see 2 errors in the log
12:52:14 iCloud kalender [CalDAV] MailClient.Accounts.ConnectionException: ‘Element’ is an invalid XmlNodeType.
—> System.Xml.XmlException: ‘Element’ is an invalid XmlNodeType.

Should I delete my IOS caldendar and create a new one ? Maybe this can work ?

I have news : I deleted everything on iCloud . Now my iCloud agenda is syncing fine with the iCloud agenda on internet. So the link between iOS and internet iCloud is ok. I also deleted the account and created again in Menu → Accounts - Add Account - Calendar - iCloud calendar . But now I see another error in the log :
16:22:54 iCloud kalender [CalDAV] MailClient.Accounts.ConnectionException: The ‘calendar-data’ start tag on line 9897 position 26 does not match the end tag of ‘style’. Line 9970, position 67.
—> System.Xml.XmlException: The ‘calendar-data’ start tag on line 9897 position 26 does not match the end tag of ‘style’. Line 9970, position 67.

What can this be ?