If you look at the global numbers not all countries had a similar drop in life expentency (ie. Denmark and New Zealand had no drop) but went through similar or more severe lockdown and vaccine policies.

Do those countries have drug epidemics?

https://www.cdc.gov/nchs/pressroom/nchs_press_releases/2021/...

Blaming life expectancy drop on "undetected" covid without any evidence is not very scientific. I can say it's undetected drug overdoses too.

Maybe either root the logic in facts, or don't write off alternative possibilities.

Yes, exactly. Lockdowns and vaccines are not the only covid prevention policies. Stimulus checks and unemployment compensation (along with their universality and the ease and speed of obtaining them), testing availability, and general healthcare access also fit into the "covid prevention policies" category, and can be reasonably suspected to have had some impact on life expectancy.