Missing 4xx log entries when compared to the hrsp_4xx metric

I am observing a pattern of a large increase in value of hrsp_4xx without matching log entries.

Observing the stats I noticed that the hrsp_4xx metric is increased every 5-6 minutes by the value of 70+. In between these bumps, other values do have a corresponding 4xx log entry. When compared to the backend stats I can only match 4xx entries between these unexplained bumps.

How can I debug to determine which events are causing these increases of hrsp_4xx?

Example graph:

Seeing a similar issue with HAProxy version 2.0.14.

Working in a micro services deployments setup whereby each micro service is communicating with the partner service via associated sidecar proxy (HAProxy). No 4xx errors logged in HAProxy logs, but the value for hrsp_4xx metric as seen on the stats page shows increased count per minute.

Unable to understand the root cause as yet.