When applying colour corrector, blur, and crop effects with source nodes, you can apply the effects to the result of the source or to the input clip of the media.
To apply an effect to the result of the source:
You can enable any combination of colour corrector (CC), blur, and crop. For example, with a source node referring to an input clip with a blur, combined with a 3D text node, you can see the difference by enabling and disabling Blur in the Source menu.