The article claims that 1.1.1.1 is a joint project between CloudFlare and Mozilla. But the source it links to for that never mentions Mozilla.
[1] https://developers.cloudflare.com/1.1.1.1/commitment-to-priv...
>Mozilla and Cloudflare are deploying their own DNS recursive resolver
>Mozilla/Cloudflare’s 1.1.1.1 operate such open DNS recursive resolvers
And on my isolated network, which has no routed access to the internet?
> Provides an optional resolver mechanism for Firefox that allows running together with or instead of the native resolver.
> "localhost" and names in the ".local" TLD will never be resolved via DOH.
> TRR is preffed OFF by default
WRT to the Cloudflare/Mozilla "partnership", see this discussion [0] from 11 days ago (spoiler: it's a "Shield study").