eg
```
"impacts": [
            {
              "severity": 3,
              "description": "Searches might return slower than usual. Fewer redundant copies of the data exist on 2 indices [.ds-logslogslogs-2022.03.29-000001, my-index-000001].",
              "impact_areas": [ "search" ]
            }
          ]
```
server/src/main/java/org/elasticsearch/cluster/routing/allocation/ShardsAvailabilityHealthIndicatorService.java
private boolean available = true; 
        private int unassigned = 0;
        private int unassigned_new = 0;
        private int unassigned_restarting = 0;
        private int initializing = 0;
        private int started = 0;
        private int relocating = 0;
        private Set<String> indicesWithUnavailableShards = new HashSet<>();
        public void increment(ShardRouting routing, NodesShutdownMetadata shutdowns) {
            boolean isNew = isUnassignedDueToNewInitialization(routing);
            boolean isRestarting = isUnassignedDueToTimelyRestart(routing, shutdowns);
            available &= routing.active() || isRestarting || isNew;
            if ((routing.active() || isRestarting || isNew) == false) {
                indicesWithUnavailableShards.add(routing.getIndexName());
            }
            switch (routing.state()) {
                case UNASSIGNED -> {
                    if (isNew) {
                        unassigned_new++;
                    } else if (isRestarting) {
                        unassigned_restarting++;
                    } else {
                        unassigned++;