It seems like the "messages" subscription stopped working since Meta upgraded to version 21.0. All other subscriptions seem to work. I have another app with v20.0 configured and everything seems to work there. There is a similar issue described here: https://stackoverflow.com/questions/79175537/whatsapp-business-api-messages-webhook-not-triggering-even-with-manual-testin

What should I do? This seems like a serious bug.