Can't find them at the moment (check the Swift forums), but the two big issues I've seen reported are both in TaskGroup. One is a runtime crash under certain conditions, the other a major performance bottleneck when adding thousands of child tasks to a group. Both have workarounds, but they can hit you when using back deployment or any OS that has the 5.5 runtime (iOS 15 - 15.3 for instance). Wouldn't be showstoppers for me, just something to be aware of.