What?

"Molly is open-source just like Signal. But Signal uses Google's proprietary software to provide some key features.

To support a 100% free and auditable app, Molly comes in two flavors: one with proprietary blobs like Signal and one without. They are called Molly and Molly-FOSS, respectively. You can install the flavor of your choice at any time, and it will replace any previously installed version. The data and settings will be preserved so that you do not have to re-register."