onBlurAsync on a field also called when submitting the form, bug or expected behavior?

<form.Field
    name="email"
    validators={{
        onBlurAsync: async ({ value }) => {
            await new Promise((resolve) => setTimeout(resolve, 2_000));
            // Fake check, just for demo purposes
            return value.includes('error') && 'Email already exists, login instead?';
        },
    }}
    children={(field) => {
        return /* */;
    }}
/>