We somehow missed the moment that everyone's beloved Retrofit hasn't been released for more than three years, since May 2020.
Maintainers in discussions say that it's stable enough in itself, and they're busy on other projects. Understandable.
In general I would agree, if I hadn't updated the project to AGP 8 this week, which now enables R8 full mode by default. And the app starts crashing on the very first request in release, because the current rules bundled inside Retrofit don't cover all the breaking changes of R8.
So, for your information, in stable Flamingo projects are created with AGP 8 by default, meaning in a newly created project by adding Retrofit you'll simply crash in the release version right out of the box. Who's more to blame here is an open question, but I would like to see a little more mobility from a library that is unconditionally the industry standard.
For now I disabled full mode via the property android.enableR8.fullMode=false, since I wasn't ready to write all the necessary rules myself. We'll live like this until everyone adapts.