Shard allocation - strange behaviour of index tier preference

Can't get it to work. I created a brand new 2h/2w cluster.

# Creating the index
PUT test1
{
  "settings": {
    "index.routing.allocation.include._tier_preference": null,
    "number_of_replicas": 2
  }
}

# GET _cat/shards/test1?v 200 OK
index shard prirep state      docs store ip            node
test1 0     p      STARTED       0  225b 10.47.192.173 instance-0000000000
test1 0     r      STARTED       0  225b 10.47.192.99  instance-0000000001
test1 0     r      UNASSIGNED                          

# GET _cluster/allocation/explain 200 OK
{
  "index": "test1",
  "shard": 0,
  "primary": false,
  "current_state": "unassigned",
  "unassigned_info": {
    "reason": "INDEX_CREATED",
    "at": "2023-03-07T22:56:28.660Z",
    "last_allocation_status": "no_attempt"
  },
  "can_allocate": "no",
  "allocate_explanation": "Elasticsearch isn't allowed to allocate this shard to any of the nodes in the cluster. Choose a node to which you expect this shard to be allocated, find this node in the node-by-node explanation, and address the reasons which prevent Elasticsearch from allocating this shard there.",
  "node_allocation_decisions": [
    {
      "node_id": "79fDvTXCTr24DjmsUMsYOA",
      "node_name": "instance-0000000003",
      "transport_address": "10.47.192.117:19037",
      "node_attributes": {
        "region": "unknown-region",
        "instance_configuration": "gcp.data.highstorage.1",
        "server_name": "instance-0000000003.4f379901a9b14417a3e141d745799f8f",
        "data": "warm",
        "xpack.installed": "true",
        "logical_availability_zone": "zone-1",
        "availability_zone": "us-west2-b"
      },
      "node_decision": "no",
      "weight_ranking": 1,
      "deciders": [
        {
          "decider": "data_tier",
          "decision": "NO",
          "explanation": "index has a preference for tiers [data_content] and node does not meet the required [data_content] tier"
        }
      ]
    },
    {
      "node_id": "NZ2kKMF3R-WkhNF56SCJgA",
      "node_name": "instance-0000000002",
      "transport_address": "10.47.192.127:19677",
      "node_attributes": {
        "region": "unknown-region",
        "instance_configuration": "gcp.data.highstorage.1",
        "server_name": "instance-0000000002.4f379901a9b14417a3e141d745799f8f",
        "data": "warm",
        "xpack.installed": "true",
        "logical_availability_zone": "zone-0",
        "availability_zone": "us-west2-c"
      },
      "node_decision": "no",
      "weight_ranking": 2,
      "deciders": [
        {
          "decider": "data_tier",
          "decision": "NO",
          "explanation": "index has a preference for tiers [data_content] and node does not meet the required [data_content] tier"
        }
      ]
    },
    {
      "node_id": "ZktlgqMhQF6opcfiq9mP6g",
      "node_name": "instance-0000000001",
      "transport_address": "10.47.192.99:19787",
      "node_attributes": {
        "region": "unknown-region",
        "instance_configuration": "gcp.data.highio.1",
        "server_name": "instance-0000000001.4f379901a9b14417a3e141d745799f8f",
        "data": "hot",
        "xpack.installed": "true",
        "logical_availability_zone": "zone-1",
        "availability_zone": "us-west2-b"
      },
      "node_decision": "no",
      "weight_ranking": 3,
      "deciders": [
        {
          "decider": "same_shard",
          "decision": "NO",
          "explanation": "a copy of this shard is already allocated to this node [[test1][0], node[ZktlgqMhQF6opcfiq9mP6g], [R], s[STARTED], a[id=neRr7bqfTRqodGpKFEjcGw], failed_attempts[0]]"
        }
      ]
    },
    {
      "node_id": "q_tYt6RFSHO5efwV-IAjsQ",
      "node_name": "instance-0000000000",
      "transport_address": "10.47.192.173:19307",
      "node_attributes": {
        "region": "unknown-region",
        "instance_configuration": "gcp.data.highio.1",
        "server_name": "instance-0000000000.4f379901a9b14417a3e141d745799f8f",
        "data": "hot",
        "xpack.installed": "true",
        "logical_availability_zone": "zone-0",
        "availability_zone": "us-west2-c"
      },
      "node_decision": "no",
      "weight_ranking": 4,
      "deciders": [
        {
          "decider": "same_shard",
          "decision": "NO",
          "explanation": "a copy of this shard is already allocated to this node [[test1][0], node[q_tYt6RFSHO5efwV-IAjsQ], [P], s[STARTED], a[id=HQbhwF4zTyalKa3rCQW9cA], failed_attempts[0]]"
        }
      ]
    }
  ]
}
# GET _cluster/allocation/explain 200 OK
{
  "index": "test1",
  "shard": 0,
  "primary": true,
  "current_state": "started",
  "current_node": {
    "id": "q_tYt6RFSHO5efwV-IAjsQ",
    "name": "instance-0000000000",
    "transport_address": "10.47.192.173:19307",
    "attributes": {
      "server_name": "instance-0000000000.4f379901a9b14417a3e141d745799f8f",
      "instance_configuration": "gcp.data.highio.1",
      "region": "unknown-region",
      "availability_zone": "us-west2-c",
      "logical_availability_zone": "zone-0",
      "xpack.installed": "true",
      "data": "hot"
    },
    "weight_ranking": 3
  },
  "can_remain_on_current_node": "yes",
  "can_rebalance_cluster": "no",
  "can_rebalance_cluster_decisions": [
    {
      "decider": "rebalance_only_when_active",
      "decision": "NO",
      "explanation": "rebalancing is not allowed until all replicas in the cluster are active"
    },
    {
      "decider": "cluster_rebalance",
      "decision": "NO",
      "explanation": "the cluster has unassigned shards and cluster setting [cluster.routing.allocation.allow_rebalance] is set to [indices_all_active]"
    }
  ],
  "can_rebalance_to_other_node": "no",
  "rebalance_explanation": "Elasticsearch is not allowed to allocate or rebalance this shard to another node. If you expect this shard to be rebalanced to another node, find this node in the node-by-node explanation and address the reasons which prevent Elasticsearch from rebalancing this shard there.",
  "node_allocation_decisions": [
    {
      "node_id": "79fDvTXCTr24DjmsUMsYOA",
      "node_name": "instance-0000000003",
      "transport_address": "10.47.192.117:19037",
      "node_attributes": {
        "server_name": "instance-0000000003.4f379901a9b14417a3e141d745799f8f",
        "instance_configuration": "gcp.data.highstorage.1",
        "region": "unknown-region",
        "availability_zone": "us-west2-b",
        "logical_availability_zone": "zone-1",
        "xpack.installed": "true",
        "data": "warm"
      },
      "node_decision": "no",
      "weight_ranking": 1,
      "deciders": [
        {
          "decider": "data_tier",
          "decision": "NO",
          "explanation": "index has a preference for tiers [data_content] and node does not meet the required [data_content] tier"
        }
      ]
    },
    {
      "node_id": "NZ2kKMF3R-WkhNF56SCJgA",
      "node_name": "instance-0000000002",
      "transport_address": "10.47.192.127:19677",
      "node_attributes": {
        "server_name": "instance-0000000002.4f379901a9b14417a3e141d745799f8f",
        "instance_configuration": "gcp.data.highstorage.1",
        "region": "unknown-region",
        "availability_zone": "us-west2-c",
        "logical_availability_zone": "zone-0",
        "xpack.installed": "true",
        "data": "warm"
      },
      "node_decision": "no",
      "weight_ranking": 2,
      "deciders": [
        {
          "decider": "data_tier",
          "decision": "NO",
          "explanation": "index has a preference for tiers [data_content] and node does not meet the required [data_content] tier"
        }
      ]
    },
    {
      "node_id": "ZktlgqMhQF6opcfiq9mP6g",
      "node_name": "instance-0000000001",
      "transport_address": "10.47.192.99:19787",
      "node_attributes": {
        "server_name": "instance-0000000001.4f379901a9b14417a3e141d745799f8f",
        "instance_configuration": "gcp.data.highio.1",
        "region": "unknown-region",
        "availability_zone": "us-west2-b",
        "logical_availability_zone": "zone-1",
        "xpack.installed": "true",
        "data": "hot"
      },
      "node_decision": "no",
      "weight_ranking": 3,
      "deciders": [
        {
          "decider": "same_shard",
          "decision": "NO",
          "explanation": "a copy of this shard is already allocated to this node [[test1][0], node[ZktlgqMhQF6opcfiq9mP6g], [R], s[STARTED], a[id=neRr7bqfTRqodGpKFEjcGw], failed_attempts[0]]"
        }
      ]
    }
  ]
}