There was a famous case where a single person was rejected, and the cited reason was his high IQ. The particular location had a policy of rejecting extreme IQ because evidence showed that IQ is correlated with job turnover. He sued them and lost because IQ is not a protected status in the US and because there was a cited non-prejudicial reason.
But of note, it doesn’t appear to be common enough that anyone has researched it as a statistic. It’s just that despite being run by the government, police departments have enough autonomy to set their own hiring policies as long as they are legal.
There’s a lot of genuine criticisms about the police. We should focus on those. Like their half-ass training and the laws/policies that lead to harmful behavior by them and garner well-earned mistrust.