We use a webhook for receiving notifications from HealthChecks we have created on Cloudflare. In the beginning, everything was fine, but then suddenly, the messages started to always appear twice.

Deleting the notification and creating a new one on Cloudflare's side did not change a thing, and Cloudflare's devs were able to show us that in fact the webhook API is really only called once per message (notification in Cloudflare speak).

But deleting the webhook on Slack's side and creating a new one and registering it with the notifications in Cloudflare helps - for a limited time. After a few days or weeks, notifications started to come in as duplicates again.

Has anyone observed a seemingly behaviour? Does someone know how to fix this?

Cheers, Roman.