This is the 4824th most frequent Japanese word.
浮かび上がっ
"To emerge" or "to come to the surface."
Here, "浮かび上がった" is used to describe an image or reflection appearing on a surface.
湖の水面に月の光が浮かび上がった。
The moonlight floated and reflected on the surface of the lake.
In this sentence, "浮かび上がった" signifies something abstract (unease) surfacing or becoming apparent.
彼女の表情から不安が浮かび上がった。
Unease arose from her expression.
This example uses "浮かび上がって" to express the emergence or recognition of finer details upon close observation.