That seems as a weird decision by Firefox considering their relatively privacy focused image.

Not really as hiding dns alone doesn’t give you a big increase in privacy. Your isp can see what sites you visit immediately after anyway.

It could be argued that sending all your dns requests to a 3rd party by default is actually a decrease in privacy.

1.https does not mean more private. for regular browsing it does not matter 2. it is always good to have 2 browsers or use containers to seperate personal and regular stuff