Demystifying Hybrid Free/Busy: what are the moving parts?

ProfileX , GaryLowell ,I know I am very late in answering, but I can try to update the article to include this. The difference with the New Modern Hybrid Agent is that IntraOrganization connector / Org Relationship in EXO will have TargetSharingEpr set to https://<GUID>.resource.mailboxmigration.his.msappproxy.net/EWS/Exchange.asmx . And I have another article on troubleshooting Hybrid Agent: Modern HCW (Hybrid Agent): troubleshooting like a pro - Microsoft Community Hub
Also, this image from another blog, although it is for migration endpoints, it basically shows the Modern Agent configuration in EXO: Troubleshooting Hybrid Migration Endpoints in Classic and Modern Hybrid - Microsoft Community Hub