the.com/shrinking violet

means A person who is excessively shy, modest, or retiring, especially one who avoids attention.

from The violet flower has long symbolized modesty because it grows low to the ground, often hidden under leaves, and was linked in old poetry and flower-symbolism traditions to humility and shyness. 'Shrinking' simply means recoiling or drawing back from notice. The phrase fuses the two — someone who shrinks from attention the way a violet shrinks from the open sun — and appears in English usage by the early 1800s, often used slightly ironically about people who are anything but bold.