Probando

<script src="https://cdnjs.cloudflare.com/ajax/libs/iframe-resizer/4.3.6/iframeResizer.min.js"></script>
                              <script>
                                function initResizer() {
                                  iFrameResize({
                                    heightCalculationMethod: 'documentElementOffset',
                                    onScroll: ({ x, y }) => {
                                      // prevent default behavior
                                      window.scrollTo({
                                        top: y,
                                        left: x,
                                        behavior: 'smooth'
                                      })
                                      return false;
                                    }
                                  }, '#valuationFrame');
                                }
                              </script>
                              <iframe style="min-width: 100%; border:none;" title="valuation"
                                src="https://afin-inmobiliaria.valuation.realadvisor.es/appraise?language=es" id="valuationFrame" onload="initResizer()">
                              </iframe>