[detuur]

    > one.one.one.one:443:64:ff9b::1.1.1.1

Is this a typo or a weird curl-specific address format I've never heard of?

[forbiddenlake]

It's the argument to --resolve, not the desired URL.

    --resolve <[+]host:port:addr[,addr]...>
              Provide a custom address for a specific host and port pair. Using this, you can make the curl requests(s)
              use a specified address and prevent the otherwise normally resolved address to be  used.  Consider  it  a
              sort  of  /etc/hosts  alternative provided on the command line.

[detuur]

I looked right past `--resolve`, so yes that now makes sense.