you are asking what features the new ActivityPub plugin version has?
thanks for asking! ☺️
* Support for post visibility - you can choose between "public", "only followers" and "no federation".
* Attribution-Domains - that should fix the fediverse:creator issues, if you had issues
* Improved compatibility with caching plugins
https://github.com/Automattic/wordpress-activitypub/releases/tag/4.0.0
