QGIS 3.10 - Changing display name of layer

You need to use the layer id to call a specific layer instead of the layer name. Changing the name does not change the id:

project = qgis.core.QgsProject.instance()
tree = project.layerTreeRoot().children()
layer = tree[0].layer()

print(f'type={type(layer)}')  # type=<class 'qgis._core.QgsVectorLayer'>
print(f'id={layer.id()}')     # id=New_scratch_layer_83348484_7916_4fe4_a137_2b98949ba488
print(f'name={layer.name()}') # name=New scratch layer

layer.setName('new name')     

print(f'id={layer.id()}')     # id=New_scratch_layer_83348484_7916_4fe4_a137_2b98949ba488
print(f'name={layer.name()}') # name=new name