Any meta-study is going to be significantly tainted by papers regarding the use and effects of cannabis prior to 2018 in Canada because of the stigma and bias of researchers, funding sources, and politics of the time. Positive findings, or debunking negative perception, was rare. You needed to bolster the status quo - rocking the boat endangered funding.

Beyond the biases, there's not a good academic framework for drug use, intoxication, addictive behaviors, and so on. Neuroscience is slowly getting there, but good science is damn near impossible when you mix psychology and social behavior.

There's a reason for the replication crisis, and this paper blithely leaves validation of the input to the reader, as if the crisis doesn't exist.

This is oddly similar to some of the 2008 housing crisis debt abstractions - bundling shitty papers together into meta-studies, then bundling the bundles again somehow achieves legitimacy.

There are decades of reefer madness nonsense to weed out of any cannabis science. Until we have a few decades of legal use, academia isn't going to have a lot to say worth listening to.