At the moment, this is an A/B test to see if DNS over HTTPS can keep up with regular DNS in term of performance in a real-world setting. It’s an opt-in study. That’s about the extend of it.

You can explicitly enable DNS over HTTPs on recent FF versions if you want to, then you need to pick a provider. There are a few available choices out there. There’s a list on the cURL docs IIRC. Due to the standard being finalized right now, the list is understandably quite short, by there’s no particular reason you ISP shouldn’t offer a suitable DNS server in the future.

Does Google do this with their own DNS service in Chrome...or would this open the door for them to do so? I don't like the implications.

But since there's already a high risk of ISPs sniffing or even redirecting this traffic, you'd have to show that the risk for the average user is higher with CF.

It funnels all _firefox_ requests through CF, as opposed to all _$ISP_ requests. Which one is worse for the user I find hard to say, but they'd definetely generate two completely different datasets. (for example, CF's set would be international).

>This seems well-intentioned but incredibly dangerous.

Like many of the things the Mozilla Corporation has been doing these last years.