I am not too familiar with the process of webhooks because I chose not to build one due to privacy concerns. However, you might want to check if your API is still verified. I had this issue with my WhatsApp API when I didn't have the correct privacy policy and terms and conditions linked to the website for my Meta Developers verification. It will be removed by Meta for legal purposes, so check to see if it still has the verified green mark in the Meta Business Suite. It is very common for your account to be flagged within hours if you do not have these policy clearly linked on the homepage or top page of the website associated with your verified Meta Developers account. If this turns out to be the issue and you need help making one, you can do a simple google search to find out how to create a privacy policy and terms and condition policy and link it to your website's homepage.

Hey Eugene, I checked this possibility you have mentioned and it seems that the business is verified. Do you have any other ideas? This is very urgent as our WhatsApp bot is totally off.. :/