Unfortunately, the Debugger's Beret (or "purple beret") is no longer awarded to players, and hasn't been available for several years. At this time, there are no plans to reintroduce this specific item or a similar incentive.
Originally, this item was awarded to players who reported particularly complex or impactful bugs. Unfortunately, this incentive to a high volume of duplicate tickets, along with an increase in inaccurate or unhelpful bug reports.
These days, we often credit players who report bugs with a thank-you note in the changelog when applicable. This approach has been a more balanced incentive for helping fix the game.