It's working for me. Try this:
<!-- Save this as test-cors.html and open in a browser -->
<!DOCTYPE html>
<html>
<body>
<script>
fetch("https://piefed.social/api/alpha/comment?id=6527216", {
method: "GET", // or "POST", etc.
headers: {
"Content-Type": "application/json"
}
})
.then(response => response.text())
.then(data => console.log("Success:", data))
.catch(error => console.error("CORS Error:", error));
</script>
</body>
</html>