The beta flag is needed when you are participating in the beta testing program. What they expect of beta testers is not very prominently documented. It can be researched in their forum. IIRC you need to be registered and logged in at the forum to see the relevant content. Or if you know exactly what you are doing, ignore their virtually undocumented expectations.
If you are in the slightest tiniest doubt, don't use the beta flag.
If you are in the slightest tiniest doubt, don't use the beta flag.