I had been using publinks to my calendars in nextcloud because I didn’t want to expose my password in anyway within the nextcloud configuration, even the secrets file. However, even with this setting I had the frustrating issue where calendar event series didn’t work such as M-F every week at 5:30. At the time, I just thought it was a defect and was begrudgingly waiting for a fix, per this bug: Calendar: Repeat events do not show in all views · Issue #40127 · home-assistant/core · GitHub
However when 2022.2 was released, all of my calendars stopped working completely and I hadn’t had time to investigate if it was a HA issue or a nextcloud issue until recently. I found this bug
This indicates that the public subscription links are really just .ics ical file links and only accidentally worked even to a slight degree in HomeAssistant
The solution to use real CalDav links from next cloud is to follow the documented examples for CalDav. However I still didn’t want to enter my account password, even a app-password. What I did to solve this is to create an account in Nextcloud called “Assistant”, setup TOTP authentication and generate an app-password for it. Then I shared the calendars I wanted to appear in home assistant to this account which allows them to work correctly in Homeassistant.
Additionally, the issue that repeating events did not work is also resolved now using a real CalDav connection.