This is a known issue in ArcGIS Server 10.7.1 and is fixed in ArcGIS Server 10.8. Here is how it looks now in ArcGIS Server 10.8.
{
fieldName: "Family",
modelName: "family",
label: "Family",
mostFrequentValues: [
"Basic Wall",
"",
"单扇平开木门4",
"单层双列",
"系统嵌板",
"单层单列",
"Rails",
"单层三列",
"Floor",
"墙饰04",
"楼顶",
"门口台阶",
"墙饰",
"墙饰02",
"墙饰03",
"墙饰05"