Talvez isso aqui te ajude :

https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver

const targetNode = document.querySelector("body");

const observer = new MutationObserver((mutationList, observer)=> {
mutationList.forEach( (mutation) => {
if(mutation.type === 'childList') {
console.log(mutation.addedNodes);
}
})

});
observer.observe(targetNode, {
childList: true,
});

setTimeout(() => {
const someElement = document.createElement("div");
someElement.className = "some-element";
someElement.textContent = "Some Element";
document.body.appendChild(someElement);
}, 1000);