Most people voicing "concern" are saying "crime is increasing" and usually blaming either current politicians and/or progressive policies for the "increase". It's almost always accompanied by either a "vote for me" or some screed on how we have "gone soft on crime".
The fact that talk about crime rates is usually an attack on progressive policies usually means progressives usually also respond in an ACKSHUALLY manner followed by a wall of anarchist crime theory which must account for all (not just some) of any disparity, because if it does not then you have stabbed your own side in the back.
Whatever you think about Elizier Yudowsky, I think he hit this one right on the nail.
https://www.lesswrong.com/posts/PeSzc9JTBxhaYRp9b/policy-deb...
https://www.axios.com/2023/12/28/us-murder-violent-crime-rat...
There are obviously lots of reasons for this having nothing to do with crime policy, such as the economic shock of covid. That being said, I don't think its true at all it is straightforwardly settled how to reduce crime.
Pretty much all people I have read on this suggest penalizing gun possession crimes more would decrease the violent crime rate. It's part of the reason murder rate in places like NY is relatively low. That said, prosecuting more people for probation violations or gun possessions is a a policy that cuts against both conservative ideology (because they are pro gun) and progressive ideology (because it will require a larger prison population that will be disproportionately minority)