Life expectancy at birth has risen rapidly during the past century due to a number of factors. These include a reduction in infant mortality, rising living standards, improved lifestyles and better education, as well as advances in healthcare and medicine. Official statistics reveal that life expectancy has risen, on average, by more than two years per decade since the 1960s. In 2020, however, after the outbreak of the COVID-19 pandemic, this indicator declined in 25 EU countries compared to 2019, the exceptions being Denmark and Cyprus. In 2023, life expectancy at birth was equal to or higher than in 2019 in 21 EU countries. By contrast life expectancy fell in 6 EU countries: Finland (-0.5 years), the Netherlands (-0.3 years), Germany (-0.2 years) to Italy, Latvia and Austria (all -0.1 years).
From whom? There are people living alone who die in their homes and aren't discovered for months, even years. If you have a caretaker and you pass away (and the caretaker relies on your pension to pay their bills) it is trivial to just... not say anything and keep collecting the pension. In a system suffering administrative decay, wherein the elderly are already obfuscated and ignored, there are few real means of physically validating whether an individual is alive or dead.
Low natality plays a more important factor, it’s hard for people to die young, if there aren’t many young people anymore.
True, but you can weight for natality in your statistics already. The "Blue Zone" hypothesis focuses on the parts of the population already older than 60, typically with an eye towards people who are lifelong residents. That much of the methodology is sound.