Webhook validation stopped working yesterday

Since yesterday we’ve got an error for validating our event webhook:
“URL validation failed. Try again later.”

We are not aware of any change on our end. Has anything changed on Zoom side? Is there way to troubleshot this efficiently? There are no logs in Zoom dashboard with more information why it failed.

This ended up to be a problem on our end. However, one concerning things is that no email was sent from Zoom once the verification started to fail.