We have recently upgraded Elasticsearch from 6.6.1 to 7.13.2 with platinum licence. After upgraded all looks fine and when 3-4 users try to search logs parallelly we getting 504 error and when i check cluster status it says cluster went to rent and nodes are getting restart. These are configured as Kubernetes setup and nodes are running in statefulset. When i get cluster red state, i could see PODS are still up and running but service nodes getting restart. this happening very frequently and slowness after upgrade.