This site uses CMB2 (a custom-fields library that is usually bundled inside a theme or plugin) to register one or more settings pages that are readable through the WordPress REST API. To align with WordPress core conventions, a future CMB2 release will limit REST API reads of settings-page data to users who can manage those settings (administrators, typically). Most sites need no action, and nothing changes yet. If your site has a custom integration that reads these settings through the REST API, please share the guide below with your developer.