*.salesforce-setup.com domain must now be added to the company’s list of allowed domains to ensure that Setup pages in Lightning Experience load content correctly when browsers block third-party cookies. This change is only required for companies that control users’ or servers’ access to the internet through firewalls or allowlists
Where: This change applies to Lightning Experience in all editions
When: The rollout began in Spring ’24 and continues through Spring ’25. The change is first enabled in sandboxes and nonproduction orgs and then in production orgs