In AXIsolatedTree::applyPendingChanges(), when processing m_pendingSubtreeRemovals, we start by taking the last axID in the Vector and using it to get the associated nodeForID(). Then we call AXCoreObject::detach(AccessibilityDetachmentType::ElementDestroyed), which in turn calls AXIsolatedObject::detachRemoteParts. Currently, the implementation of this function loops over m_childrenIDs and detaches those children from `this`, and then clears m_childrenIDs.

Then, we jump back to AXIsolatedTree::applyPendingChanges() and run this line of code:

m_pendingSubtreeRemovals.appendVector(object->m_childrenIDs);

Which does nothing because we cleared m_childrenIDs as part of detachRemoteParts.