I'm not sure specifically which 'god forbid real story' you're referring to. It could be a very personal or specific account that only the person using that term knows about. Maybe it's a story that involves something difficult or tragic that one hopes never actually happened.
One example could be a story of a family who lost their home in a natural disaster like a tsunami. The force of the water just swept away their entire livelihood, and they were left with nothing. It's a 'god forbid real story' because no one wants to experience such a tragic event in real life.
Well, God Forbid is purely fictional. It's the imagination of the creator and not drawn from actual happenings. There are no real-life equivalents or inspirations for this story.
God Forbid on Hulu is most likely not a true story. Usually, such shows are created for entertainment and may incorporate fictional plots and characters.
'God forbid' is kind of like a plea to a higher power to prevent something. And 'based on true story' tells us that what we are about to hear or see has some factual basis from real events. For example, in a movie that says this, the overall plot or some elements of it are drawn from things that actually happened in the world, but at the same time, we hope such a situation (usually a difficult or bad one) doesn't happen again, which is what 'god forbid' implies.
Sure. There are many movies like this. For instance, 'Schindler's List'. God forbid that the Holocaust ever happened again. But it was based on a true story about Oskar Schindler saving Jews during that terrible time in history.