Fixed regression

Author: sakno

src/DotNext.Threading/Threading/CancellationTokenMultiplexer.Scope.cs

@@ -74,7 +74,7 @@ private static CancellationToken GetToken(ValueTuple<object> value)
         /// <summary>
         /// Gets the cancellation origin if <see cref="Token"/> is in canceled state.
         /// </summary>
-        public CancellationToken CancellationOrigin => source?.Token ?? GetToken(multiplexerOrToken);
+        public CancellationToken CancellationOrigin => source?.CancellationOrigin ?? GetToken(multiplexerOrToken);
 
         /// <inheritdoc/>
         public void Dispose()