The WeasyPrint Python package relies on the woff options provided by fonttools (see https://github.com/Kozea/WeasyPrint/blob/master/pyproject.toml#L22). That’s not the case of dev-python/weasyprint-53.0, that depends only on dev-python/fonttools without explicit woff support.
dev-python/fonttools actually has a "test" use flag installing the dependencies required for woff support. I don’t know if it’s possible to add a "woff" use flag to dev-python/fonttools with the same dependencies as "test", and make dev-python/weasyprint require this use flag.
This fix is not urgent at all. WeasyPrint should work fine without fontools’ woff support, even if it’s not officially tested and supported.