Channel#broadcast doesn't work like `broadcast_to`

[jwoertink]

Channel has a broadcast and self.broadcast_to method. In production, I've been using the class method for sending chat messages.

class ChatChannel < ApplicationCable::Channel
  def subscribed
    stream_from("chat:room_1") 
  end
  def perform(action, data)
    ChatChannel.broadcast_to("chat:room_1", "some message")
  end
end

This works great. Then while doing some code cleanup I was questioning why I wasn't using the instance method to broadcast in here... So I change it to this

class ChatChannel < ApplicationCable::Channel
  def subscribed
    stream_from("chat:room_1") 
  end
  def perform(action, data)
    broadcast("some message")
  end
end

In my mind, this method was cleaner. I tested locally and in staging and it worked fine. No issues.. So I deploy to production, and my chat wasn't necessarily completely broken, but it also wasn't working great. When sending a chat message, only some people would get it. Not everyone. Then when everyone would do a hard refresh, other people would get the messages and new people wouldn't. It was almost like it could only broadcast to like 5 people, but with 10 in chat, half the people wouldn't get it....

It's a very confusing issue. Reverting back to using the broadcast_to fixes it all for me, so I have no clue but wanted to at least document it.