Calendars on iOS: secondary calendars no more visible starting 2022

Hi everyone,
is it only me? Starting exactly 1/1/2022, on two iOS based devices (iPhone and iPAD) I can only view appointments on my principal calendar. Two sub-calendars are there, and nothing changed on Thunderbird and Web views, are no more visible on iOS. Any hint?

I don’t know what you mean with “sub-calendars”, but I have several calendars in my account (Nextcloud 22.2.3) and they all do get properly synced to iOS 15.2 and macOS 12.0.1.

Sorry for the improper name, I was referring to the “main” (defaul) user
calendar and two additional calendars created under the same user. As an
example for user “my”:


On Thunderbird (Lightning) all calendars are (still) visible.
On iOS, while 1. is visible, the others 2. and 3. are listed but
appointments are no more visible since 2022, regardless of the calendars
being activated or not. Sounds like some upgrade or change of behaviour
but I can’t see anything different in log files.

In iOS the path in use in this case is:


which is an auto-discovery path for all calendars available to the user
I guess.