So, the Nokia support replies and said that this is an App issue of DAVx5 but I have to wait for future Updates of the Phone too The support isn´t good and the 7.2 is a buggy phone with a lot of problems. All updates and patches bringing new problems. I decided to send it back and buy another phone. I hope this will help.
icloud Reminders Sync Problem
Reminders sync doesn’t work after Apple update the app. https://support.apple.com/HT210220
You can look the link. I can not write my problem clearly due to my English level. Sorry.
We know. When you update the Reminders in iOS 13, Apple removes CalDAV support for Reminders, so that they can’t be synchronized anymore.
I have added it to “Known problems” here, too: https://www.davx5.com/tested-with/icloud