Fluentd pods are being frequently restarted

Issue

When running oc get pods on the openshift-logging namespace, it can be seen that some of the Fluentd pods have a large number of restarts.

$ oc get pods -n openshift-logging -l component=fluentd
fluentd-g6sp9                                 1/1    Running    10         9d
fluentd-hs7kd                                 1/1    Running    23        9d
fluentd-jdp97                                 1/1    Running    0         9d

Looking at the YAML of one of these pods shows that the Fluentd container in the pod has been Out of Memory (OOM) killed previously. This can be seen with exitCode: 137 along with reason: OOMKilledin the below output.

$ oc get pod fluentd-hs7kd -o yaml -n openshift-logging

lastState:
  terminated: {containerID: 'cri-o://df1935b43fa722dc27e25c55fed8dec00ba5e08aba21eb13047ebf9bdbc4a379', exitCode: 137, finishedAt: '2022-03-23T09:47:26Z', reason: OOMKilled, startedAt: '2022-03-21T22:52:50Z'}
name: fluentd