fly in the ointment: Today's thought November 8, 2020 n (idiomatic) Something (especially a minor thing) which ruins or spoils everything else, or makes it less pleasant; a nuisance or problem; a disagreeable or unpleasant detail.

fly in the ointment , n :
(idiomatic) Something (especially a minor thing) which ruins or spoils everything else, or makes it less pleasant; a nuisance or problem; a disagreeable or unpleasant detail.