Canadian here - I don't know of any data that addresses your question about marijuana, and I'm not even really sure what that data would look like. Could you give an example of data on this topic that might be interesting?
My gut feeling is probably not, legalizing marijuana definitely made marijuana more popular, but I haven't seen any reason to believe it's increasing the popularity of still illegal drugs or alcohol (the sources of these deaths). If anything I would expect that it competes with them (but again have no data to back that up).
Not sure what data would show that, maybe if there was a strong increase associated in time with legal drug policy change(s)? Other than that, I suppose a link between prosecutions and deaths...
I worry that lockdowns haven't helped situations like this, but saying that is... inflammatory...
My gut feeling is probably not, legalizing marijuana definitely made marijuana more popular, but I haven't seen any reason to believe it's increasing the popularity of still illegal drugs or alcohol (the sources of these deaths). If anything I would expect that it competes with them (but again have no data to back that up).