the.com/understatement
Saying a little so the listener feels the lot.
means Deliberately describing something as less significant than it really is, usually for irony, modesty, or effect.
from Plain English carpentry: under (below) plus statement, first nailed together in the 1800s to name speech that aims deliberately low.
British sportNational pastime: calling a disaster a bit awkward
Named figureRhetoricians dubbed it litotes, the not-bad cousin
Power moveRestraint hits harder than any exclamation point