Area Calculation doesn't work after reprojecting the Vector

I’m trying to change the projection of resolve ecoregions data to EPSG:32648.
Unfortunately, when I changed the projection, the command line for calculating the area doesn’t work.

Here is my code :

//** Center on the Region of Interest
Map.centerObject (roi,10);

//** Import Ecoregion
var ecoRegions_raw = ee.FeatureCollection("RESOLVE/ECOREGIONS/2017")
                .filterBounds(roi)

var filtered = ee.Filter (ee.Filter.noNull())
                
print ('--Dataset properties--',ecoRegions_raw);

//** Reproject dataset into EPSG:32648
var projection = 'EPSG:32648';

//** Apply Reprojection and transformation
var transformer = function(a_feature) {
  var transformed_feature = a_feature.transform(projection, 0.001);
  return transformed_feature;
};

var ecoRegions = ecoRegions_raw.map(transformer);

print(ecoRegions);

//** Set up color
var colorUpdates = [
                  {ECO_ID: 204, COLOR: '#B3493B'},
                  {ECO_ID: 245, COLOR: '#267400'},
                  {ECO_ID: 259, COLOR: '#004600'},
                  {ECO_ID: 286, COLOR: '#82F178'},
                  {ECO_ID: 316, COLOR: '#E600AA'},
                  {ECO_ID: 453, COLOR: '#5AA500'},
                  {ECO_ID: 317, COLOR: '#FDA87F'},
                  {ECO_ID: 763, COLOR: '#A93800'},
                  ];

//** loop over all other features and create a new style property for styling
//** later on
var ecoRegions = ecoRegions.map(function(f) {
  var color = f.get('COLOR');
  return f.set({style: {color: color, width: 0}});
});

//** make styled features for the regions we need to update colors for,
//** then strip them from the main asset and merge in the new feature
for (var i=0; i < colorUpdates.length; i++) {
  colorUpdates[i].layer = ecoRegions
      .filterMetadata('ECO_ID','equals',colorUpdates[i].ECO_ID)
      .map(function(f) {
        return f.set({style: {color: colorUpdates[i].COLOR, width: 0}});
      });

  ecoRegions = ecoRegions
      .filterMetadata('ECO_ID','not_equals',colorUpdates[i].ECO_ID)
      .merge(colorUpdates[i].layer);
}

//** Use style property to color shapes
var imageRGB = ecoRegions.style({styleProperty: 'style'});

//** Visualize the Ecoregion dataset
Map.addLayer(imageRGB, {}, 'RESOLVE/ECOREGIONS/2017');

//** Calculating area for each feature using function
var withArea = ecoRegions.map(function(f) {
  var clipped = f.geometry().intersection(roi)
  return f
    .set('Feature_Area_ha', f.area().divide(10000))
    .set('ROI_Area_ha', clipped.area().divide(10000))
})
print ('--Resolve Ecoregion 2017 by AOI--',withArea)

//** Extract ECO_NAME and set as property
//** within for each Feature collection
var Collection = withArea.map(function(feature) {
    var feature_id = feature.id();
    var eco_name = feature_id;
    return feature.set('id',eco_name);
});//end of map function

print(Collection)

//** Create List
//** The list of keys cannot contain duplicates so this is using 
var biome_names = ee.List(Collection.aggregate_array('BIOME_NAME'));
var area = ee.List(Collection.aggregate_array('ROI_Area_ha'));
var out_dict = ee.Dictionary.fromLists(biome_names,area);
print('--Area (Ha) by Biome Name--', out_dict);

Do you know why area calculation doesn’t work after reprojecting the vector?