Phabricator is an open source project. It was integrated years ago. It did not succeed as a project and we suffered the consequences. Tons of issues live on https://phabricator.whonix.org/, and we want to get rid of it.
As a whole, hosting applications is not what we want to spend our time doing when we can avoid it. We have discussed gitea/codeberg before, but this sort of thing takes time away from meaningful development tasks. Github is fine for us for now. Gitlab was good but we ran in to storage limit issues.
I would like to use a more modern FLOSS Jira alternative for ticket tracking, but we get by with discourse for now.
self hosting is simple until it isnt. It takes time and resources. It costs money. There is DNS, TLS, server configuration, software dependencies, updates, and other things to maintain. On top of that, you have the issue of maintainers disappearing…when we go away, all it does is leave patrick with a bunch of headaches