bottled-up resentment

Translations
сдерживаемое недовольство
Her bottled-up resentment finally exploded during the meeting.
Ее сдерживаемое недовольство, наконец, выплеснулось во время встречи.
Definitions
Bottled-up resentment refers to feelings of anger, bitterness, or displeasure that a person keeps hidden or suppressed instead of expressing openly. Over time, these unexpressed emotions can build up and potentially lead to emotional distress or conflict.
Words
resentment

noun
недовольство