Official announcement from Brave:
Get a preview of Brave’s upcoming changes with Brave Dev
Brave Dev is our unpolished and unfinished early preview for new versions of Brave. These releases show our work in progress and they aren’t for the faint-of-heart. Brave Dev showcases the newest advances that we’re bringing to your browser, but it’s a prototype, not a reliable daily driver. Try it out only if you’re looking for a little extra spice and adventure in your browsing.
This Dev version is an early, untested version with incomplete features which are in progress. We value your feedback and assistance in testing this early version of Brave Desktop.
We enabled crash reporting by default to help us improve the stability of future versions of Brave.
What on Earth are you waiting for? Go try it out!
Note: Downloading/installing the Developer build will NOT replace the current live version of Brave. You can have them both running in parallel on the same machine.
If you want to leave us feedback on the Dev build, you can leave it in the Developer Builds category here in Community.