It looks like it’s not open source.
You might want to post this in a Linux community then instead of the open source community
You can do it yourself:
And if you start eating a properly wrapped one, it turns into a quiche 🤔
That looks… really inconsistent
I think it might be this bug
If you don’t want to tinker with a Raspberry Pi, a simpler alternative would be AdGuard DNS
https://adguard-dns.io/en/public-dns.html
(Configure manually -> Routers)