Fentanyl has had a ton of coverage so I’m not sure why you think nobody is talking about it but I suspect that our limited response mostly has to do with the degree to which drug problems are often symptoms of social problems we’ve chosen not to do with.

The article specifically details the different factors in the overall decline in expected longevity. COVID is the largest but definitely not the only one:

https://static.scientificamerican.com/sciam/assets/Image/202...