open secret
US /ˈoʊpən ˈsiːkrət/
UK /ˈoʊpən ˈsiːkrət/

1.
rahasia umum
a fact that is supposed to be secret but is actually known by many people
:
•
It's an open secret that they are planning to get married.
Ini adalah rahasia umum bahwa mereka berencana untuk menikah.
•
His affair with his assistant was an open secret in the office.
Perselingkuhannya dengan asistennya adalah rahasia umum di kantor.