The short answer is: I don't know because it doesn't depend on me.
The long story is that the people responsible for these packages have discussed and they still consider Brotli as not mature enough to be included in Nginx. You can find some of these discussions in Google.
As you can read on our website:
Ethical Use Of Software
Webinoly is an Enterprise Grade Tool with full commitment to transparency.
We are very serious about the package selection we use to build your server LEMP stack, we always use official and well-known sources (PPA’s).
It’s important to us that you know that we never compile or modify these packages and we never include or use any third-party untrusted software.
We use this Nginx PPA, very well-known and maintained by some respectable Ubuntu dev-team members and as you can see (for example in this post) some decisions are made including the Ubuntu Security Team.
That's why we trust and use this package!
You can see in the official Brotli GitHub Repo, that is no very actively maintained, in the commit history you can see a lot of months (almost a year in some cases) with no updates.
In a personal opinion and vision I have to tell that I want to maintain Webinoly more on the "Enterprise" and "serious" side of the business.
I'm pretty sure it will be included in the future, but we need to wait until that happens.
