As Cloudflare says: "Oblivious DoH protocol is a practical approach for improving privacy of users, and aims to improve the overall adoption of encrypted DNS protocols without compromising performance and user experience on the Internet."
Here's the detailed information about this new protocol: https://blog.cloudflare.com/oblivious-dns/
I suggest that Mozilla explore this option since they have a good relationship with Cloudflare. There are several implementations, all of which are open source. It would be convenient to use the implementation written in Rust (odoh-rs), taking advantage of the virtues of this programming language and its simple integration into Firefox.