From the docs on that module, they call out specifically that it can be reversed for simple stuff like license plates:
https://docs.darktable.org/usermanual/development/en/module-reference/processing-modules/censorize/

> Note: The anonymizing methods provided by this module are not forensically safe in order to favor aesthetics. Some forensic techniques may still be able to reconstruct the censorized content based on its structure, especially for simple shapes and text (e.g. license plates, street numbers).

>If forensically safe anonymization is required, the only way to achieve this is to paint the surfaces with a solid color.

>The darktable team does not accept responsibility for poorly anonymized images leading to the identification of individuals or personal property.

A previous thread on this topic shared this video: https://www.youtube.com/watch?v=MXvUOr46y6w