Another aspect here I think is the generalized fear and anxiety present in young people. Having spoken to some family members in the 15-18 age bracket, the message they seem to be receiving is that they are without a future... they won't be buying homes, they won't be getting high paying jobs, and that the system is not going to work in their favor. I think people of this age are uniquely feeling mortal and vulnerable in a way teens typically have not, causing them to be more hesitant to risk losing their mind which they may need to protect themselves down the road. But they also are modern teenagers, not only low in willpower but also coddled by their smartphones, which is why technology addiction is the go to "safer" alternative to habitual drug use.
Also, you typically need to be unsupervised with friends to get into drugs, something teenagers no longer have access to compared to 10-15 years ago. If we look at the social decline due to the pandemic, what made experts think these kids would bounce back? They are forever changed, and will forever be less social than other generations because they missed out on formative experiences.