We have added a new webhook event eshop:mandatoryFields, which is emitted when “Required fields” on admin screen /admin/required-fields/ (Admin » Settings » Customers » Required Fields) get changed. Settings on this page affect fields, which are hidden or shown, optional or mandatory, on the customer registration and order billing & delivery information screens.
The webhook contains only information on eshop affected. Actual fields settings can be retrived using Eshop mandatory fields endpoint.