Your Noise layer doesn’t take any inputs (besides self). Passing it to an nn.Sequential container won’t work, since the activation from the previous layer would be passed to the Noise layer.
I’m not familiar with your use case, but if you want to call add_noise in each forward pass, you could derive Noise from nn.Conv2d, add the noise in the forward and call the forward method of the parent class via the super() attribute.