This issue is addressed in ArcGIS Pro 2.4. When using the 2.4 alpha software, the output coordinates from the test data are transformed to use GCS_wGS_1984 lat lon values (as opposed to the input web mercator easting and northings in meters):
"type" : "Point",
"coordinates" : [
-98.069799692792529,
38.673103480618614,
0
解决办法
Run the Project tool on the input features to project them to WGS 1984 before running the Features To JSON tool.