There is no Gutenberg badge. There is only WP Requirements Compliant badge. You must understand the difference between this 2 parts.
First, and important part is that all your themes are updated and meet the current requirements - and you have 4 months to do that. If not, there will be “some consequences” (but there is no official answer what will happen to this themes). The Gutenberg Optimized attribute has nothing to do with this. So, your themes at first must be coded to meet the current requirements and that mean that themes must not be (it can but “not must”) Gutenberg Optimized to get that badge. When you are done with this changes (which are important) you can start doing on Gutenberg Optimization.
And here is what they are saying about if your item is not Gutenberg Optimized and you are turning on the “Gutenberg Optimized” to “Yes” (you have that in first post).