This issue can be observed in COO 1.2 in support case 04166176.

With the release of COO 1.1 we are getting few cases related to observability-operator and perses-operator pods are getting OOMkilled.

The default limit for observability operator is 150Mi where as for perses operator is 128Mi

I would suggest to set the default limit for these 2 operator pods to be atleast 500Mi