Thank you Ziqiao for your answer! You are right it works with 18.2.1, I didn't bother to check because the issue was active for some iOS releases now.
But that leads me to two follow up questions:
The issue is only fixed if I set my minimum target to 18.2 and that is quite a bad user experience. So there is no logic for me to fix and I have to accept that this is a bug?
Was the issue or the change of some important CoreData logic changes from iOS 17 to iOS 18 somehow communicated or acknowledged somewhere? Because it seems even though in my case it wasn't enough, the linked forum post had multiple users with a similar problem, which some of them fixed with the help of this thread. But other than those 2 threads I couldn't find any information on this. I ask because if changes like these come up in the future I would like to know how to handle these.
Thanks for your help! :)
Topic:
App & System Services
SubTopic:
iCloud & Data