Oh interesting I didn't realize. Are you talking about the `/api/v1/accounts/:id/follow` endpoint? I would have assumed it used the ActivityPub Follow activity but I'm not familiar enough with it. (https://www.w3.org/TR/activitypub/#follow-activity-outbox)
Just to be clear I'm not talking about the client-to-server interaction but the server-to-server follow interaction.
I think we're talking past each other a bit. I know we were talking about browsers but then you mentioned the API for following. There's two ways to interpret that: the way the client communicates the request to follow to its home server, or the way that server contacts the other server to take the follow action. I'm asking you which you were referring to when you say it's Mastodon specific.
The web browser protocol would only need to take you to the user's profile on your home server. The actions you request with your client after that are a separate step.
Just to be clear I'm not talking about the client-to-server interaction but the server-to-server follow interaction.