Discord will let you send a maximum of 25 "fields" in one webhook call. We use 3 for each field change Bugzilla sends us, which means if there are more than 8 changes from Bugzilla, Discord will reject the message. This clogs up the queue on the Bugzilla side because it will stop sending us webhooks until we clear it (usually by deleting the change in question out of the queue).
The webhook handler needs to split it into two (or more) messages to Discord and send them separately.