Update: Explicitly defining the actor for the task actually did not solve the issue for us. Even when all code runs on the main thread, we continue to observe this crash. At this point we have no leads or reproducible examples and have opted to just not use TaskGroup on these versions of iOS.

Thank you! I was banging my head against the wall trying to figure this out and had no idea these were UI tests. Would be nice if the template labeled them as such are provided a better indication than the subtle icon.