This is the fallback name if we cant find a parent module for your block definition.

for example, if you subclass Block and then register the block type from ipython, there is no way to discover a parent module.

How do I use custom block?

Make a proper module that you can import from, and we should discover it and place it in the sample import in the UI.

https://docs.prefect.io/v3/develop/blocks#register-custom-blocks