The report addresses potential confounding issues due to COVID. In a nutshell, clearance rates were down during 2020 and declined-prosecution rates were up in 2020, and both of those things went back to normal in 2021 (links to that are in the report in the “limitations” section). However, since they tracked re-arrest over two years for everyone, the “pandemic effect” affects (aka downward biases) the re-arrest rates for both the pre-reform group and the post-reform group.