Priority mode is live for channels

On by default, you'll see the following casts in channels:

- casts by channel hosts
- casts a channel host likes or replies to
- casts by channel top casters
- casts by people you follow
- casts by power badge users

Turn off in Settings > Casts & Users > Show me channel casts from

1/ This is the biggest change to channels since we started. 

Channels are now based on a set of intersecting social graphs:

Your social graph — who you follow

The channel host's social graph — who they interact with

Top casters — local interestingness

Power badge — global interestingness

> channel hosts social graph

Can you say more here? Effectively does the hosts (and their circle) get a boost? If there are many hosts, it applies to all?

Correct. See the quote cast for how the "what to display" in channel feeds works.