I wonder if adding a simple "Describe yourself" feature along with the image to help guide the model would fix this?

Like if the model was told he is a white male + given the image

Since it's taking a photo of the user as input, force match the ethnicity of the input photo and you're good.

Yeah, I wondered the same.

Maybe attempt to predict and match the biases of the user prompting it? That may cause the least amount of friction.

Or refuse to show images where the input data proved to be strongly correlated with sensitive traits like gender or ethnicity.

I don't have a good solution.