The expression "the elephant in the room" is a metaphorical idiom in English for an important or enormous topic, question, or controversial issue that is obvious

or that everyone knows about but no one mentions or wants to discuss because it makes at least some of them uncomfortable and is personally,

socially, or politically embarrassing, controversial, inflammatory, or dangerous.Wikipedia

DIED SUDDENLY A Modern Trend? WHY!?

THE ELEPHANT IN THE ROOM no one mentions That no one wants to discuss

THE ELEPHANT IN THE ROOM / WORLD!

Also :- Open secret

https://www.bibliotecapleyades.net/sociopolitica/esp_sociopol_mindcon30a.htm#CONCL

https://www.armstrongeconomics.com/world-news/civil-unrest/the-cycle-of-assassination-war-bottomed-in-2014/