https://www.sciencedirect.com/science/article/abs/pii/S0920996423002256

In this study, we directly examined whether congenital blindness protects against a schizophrenia-related phenotype in the methylazoxymethanol acetate (MAM) rodent model.

You could argue that rodent models are insufficient to model schizophrenia in humans since it does not appear to follow reality

From the linked paper (bolding mine):

Conclusions

The relationship between schizophrenia and congenital blindness is still unrecognized and controversial. Several studies are done in this neurodevelopmental field but so far there has been no assertion nor confirmation of the suggested hypothesis. More research is needed.

Which is a more concrete version of the conclusion from the study linked from rain_enjoyer.

Correlation is not causation.

The conclusion is based on incomplete science. Also, it's relevant to note that schizophrenia is often not diagnosed if there aren't hallucinations and a born blind person would be unlikely to have visual ones at least, even with other symptoms. Not saying that it is required for diagnosis, just that many providers would be less likely to diagnose schizophrenia rather than other similar diagnoses without that symptom. Auditory hallucinations are actually the most common, but those without visual hallucinations can be attributed to quite a few other conditions, some of which are physical rather than mental.

Anyway, the studies are very limited and incomplete and there are other things that could explain the correlation rather than it being causal.

If blind people can use their third eye, this disputes schizophrenia being an alternative reality confusion

Its actually a bit different conclusion.

The conclusion of the rain_enjoyer paper is:

While support of this hypothesis would have led to novel avenues of research and potential novel therapies, the results of current study suggest that blindness does not protect against schizophrenia.

So a conclusion of "we still dont know" is quite different.

there's also observational study on half million people that, turns out, is statistically underpowered just because congenital blindness is so rare https://jmsgr.tamhsc.edu/the-lack-of-comorbidity-between-early-cortical-blindness-and-schizophrenia/ also https://academic.oup.com/schizophreniabulletin/article-abstract/46/6/1335/5813926

the results of current study suggest that blindness does not protect against schizophrenia.

This statement read to me as suggests in that more research is needed. It suggests this thing, but to definitively state we need to do more

yeah I came in very skeptical. Another thing is that yound schizophrenics can do some goofy things that are much harder to do if one is blind. Like just go off someplace and live on the streets.