When a plugin is “bundled with the main code” that means it’s under https://github.com/discourse/discourse/tree/main/plugins - in that case, the discourse-activity-pub is not bundled with the main code 
When a plugin is “bundled with the main code” that means it’s under https://github.com/discourse/discourse/tree/main/plugins - in that case, the discourse-activity-pub is not bundled with the main code