There was a recent open issue on the project regarding the format property.

Like other answers here have mentioned, TypeBox doesn't implement string formats by default so you will need to attach them to the FormatRegistry yourself. See the linked issue for more details and examples from the official author.

It seems they want to follow strict RFC compliance when implementing said format validation, which is a big focus of the project. Here is a direct quote from the project author, taken from the issue I mentioned:

TypeBox may offer built in formats at some point in future, but at this stage, TypeBox is pending RFC compliant implementations.