Acedia
Etymology
From Greek "akēdia" (absence of care), "a-" (not) + "kēdos" (care, concern). The desert monks called it the "noonday demon," the midday torpor that made prayer and life feel pointless; it was the original name behind the deadly sin later rendered as sloth.
noun · /uh-SEE-dee-uh/
A listless spiritual apathy — the inability to care about what should matter.
What it names
A specific weary indifference, older and deeper than boredom: the collapse of the will to be engaged.
Example
The lockdown weeks slid into a gray acedia in which even the things he loved felt like chores.
Related idea
Apathy is a general lack of feeling or interest; acedia is a heavier, almost spiritual version — not just not caring, but being unable to care about things one knows to be important.