You could maybe argue that if the drop was only in small petty crime. Yeah a shopkeeper may stop reporting shoplifting after the 10th time the police don't respond. That under reporting goes down as the crime gets more serious. Your probably going to report a home break in to the cops even if you know they won't do anything since you're going to need a police report for insurance, home break ins have been steadily declining since 2018 when the police staffing "problem" started. This seriousness holds very true for murders which have dropped 12% over the past year

That's assuming the victims would be under reporting, if you're saying the police departments, government etc. Are under reporting then that's getting into conspiracy territory. Especially because we're seeing this trend reported across the nation so the conspiracy would have to be massive.

Also if the government had the ability to do this why would they start now? This idea isn't too complex so someone could have easily come up with it and started doing it a while ago. If that were the case we'd never see crime rates go up as the politicians would just under report every year and make it look like crime is going down. But we have seen reported crime go up, noticeably in 2022 , and instead of hiding that many politicians and police departments showcased it as a reason to Crack down on crime and increase there budgets.