Upcoming post stream changes - How to prepare themes and plugins

During upgrading my components, I encountered some strange code:

Firstly, I am somewhat perplexed by @user={{@post}}. Could this be a typographical error?

Secondly, why are the PluginOutlet named post-avatar-flair and the UserAvatarFlair separate elements? Additionally, why isn’t post-avatar-flair a wrapper like other nearby outlets?