Am totally having the same problems with Ios15 on ipad and iPhone. In addition to calendar freezes AND tonight tried to download the newest update 15.2 only to have it go to the black screen of death (and I thought windows was bad) and not upload. I have multiple apps that can only go so far before they close down, including Safari! also, Apple really makes it difficult to report bugs, the feedback assistant is a joke, especially if you are not a developer. Fix this fast or let us go back to 14 where it was more stabile, Steve Jobs is twirling right now!