This fixes the warning in a more correct way.
@@ -44,7 +44,7 @@ public protocol KFOptionSetter {
extension KF.Builder: KFOptionSetter { }
-class KFDelegateObserver: @unchecked Sendable {
+final class KFDelegateObserver: Sendable {
static let `default` = KFDelegateObserver()
}