It looks like marketing HTTP2Shell seems to appeal to everyone that uses HTTP, while Brotli2Shell might not wake up people that know what it is.
Now, whether it's warranted or not, that's another matter, but they know how to appeal for maximum awareness/interaction.
> while Brotli2Shell might not wake up people that know what it is.
And, most of all, is damaging to Google, which are the master of software engineering. /s