The low resolution of the 3D-export causes significant distortion of the PCB shape.
easyEDA:

third party (generated from gerber):

off topic: Generally, a STEP export with proper models like the 3D-view inside easyEDA would be nice.
            
                        
            
                                    
              
                Chrome
                  86.0.4240.185
                Windows
                  10
                                EasyEDA
                  6.4.17