These methods returns the audio source URL from Facebook messenger react component.

find-facebook-messenger-voice-source-url.js

function getReactFiber(node) {
    for (const key in node) {
        if (key.startsWith("__reactFiber$")) {
            return node[key];
        }
    }
    return null;
}

function findAudioSource(node) {
    const fiber = getReactFiber(node);
    if (!fiber) return null;

    let current = fiber;
    while (current) {
        if (current.memoizedProps && current.memoizedProps.audioEl) {
            return current.memoizedProps.audioEl.current.src; // Extract audio source URL
        }
        current = current.return; // Traverse up the React tree
    }
    return null;
}

// Run the function on the selected element in the Elements tab
console.log(findAudioSource($selectedElement));

The following doesn't work in chrome extension.
It can't find react fiber in the page.

function getFiberFromDom(node: HTMLElement | null) {
        // return all object keys of the node
        console.log('Node keys:', Object.keys(node));

        if (Object.keys(node).length === 0) {
            for (const key of Object.keys(node)) {
                if (key.startsWith("__reactFiber$") || key.startsWith("__reactInternalInstance$")) {
                    console.log('Found React Fiber:', node[key])
                }
            }
        } else {
            console.log('Could not find Object.keys');
        }

        return null
    }

    useEffect(() => {
        const handleClick = (event: MouseEvent) => {
            const target = event.target as HTMLElement
            console.log("Clicked DOM node:", target)
            getFiberFromDom(target)
        }

        document.addEventListener("click", handleClick, true)
        return () => {
            document.removeEventListener("click", handleClick, true)
        }
    }, [])

Just to publish it over here

The reason it doesn't work inside chrome extension is because the scripts executes inside a isolated environment which doesn't have access to React Fiber and all that data.

by research, we found a way to inject the code directly into the browser context instead of an isolated environment

const script = document.createElement("script");
script.src = chrome.runtime.getURL("inject.js");  // ✅ Ensure correct path
script.onload = function () {
    this.remove();  // ✅ Cleanup after execution
};
document.documentElement.appendChild(script);

the solution should be wrapped in an IIFE method with the file named inject.js