cache health check returns HTTP 500

We experience cache health check issues with GitLab (omnibus) since upgrading to gitlab-cd_12.5.3.

We run two GitLab servers, they where both updated from gitlab-ce_12.3.4 to gitlab-cd_12.5.3 on December 6th. Since that time, the health check page returns 500. Atm we run 12.5.4 with the same issue.

The screenshots below show size of the health-check output. The larger size is when the check returns a 500 error page, which is larger in size than just the bytes "success" (The weekly spikes are the 500 pages returned just during the startup phase of gitlab. These are scheduled restarts.)

The check has been running quite stable since we run it...