Take a look at these appealing Unity demos with peculiar shadows, shared by 3D Artist Shuli Neuschwanstein. The creator has been working on a custom shadow asset that works with Shader Graph and has showcased the results, along with the Shader Graph parameters.
Shuli Neuschwanstein explained that they use the camera color texture together with an override material to get the custom data through, which can be seen in the third GIF above. For the glitch effect, they pass along a random offset before sampling the Shadow Map. The creator shared a screenshot of the Shader Graph for the first demo shown above, featuring a creepy shadow of a man:
