OGC Standards are listed on the OGC Standards page.
As you will see GeoJSON is not amongst them.
Quoting the document:
GeoJSON is a commonly used format that is simple to understand and well supported by tools and software libraries. Since most Web developers are comfortable with using a JSON-based format supporting GeoJSON is recommended, if the feature data can be represented in GeoJSON for the intended use.
In laymen terms, if you have any interest in serving out geospatial data via APIs, you should consider GeoJSON as a standard.