It seems the feeds set up under ACP → System → RSS Feeds have changed with the 4.2.7 betas. They didn’t include replies before, now they do. Or am I wrong? Is that intentional? Is there a way to turn it off?

If it’s intentional, I wish such changes wouldn’t be made silently. Instead there could easily be an option to have replies included and have that turned off by default in order to not change existing implementations. I have “new content” feeds set up which I also push out to RSS services like Feedly. Now the subscribers will suddenly be flooded with reply posts, which I never intended to and never advertised. And I probably can’t even change as far as I can see. 

This was an unintentional bug and will be resolved before final. Thanks for pointing it out.