How to replace "host" value produced by filebeat with a value present in the message under the "host" object?

Question

Besides other stuff in the log file I have a host value which I want to still be present after the logs pass through filebeat {"host": "123"}. Instead of the complex JSON object under "host" which can be seen in the first code snippet I would want to have something like in the second code snippet where it is "host": "123".

Complex "host" object:

{
"@timestamp": "2024-03-20T13:33:25.932Z",
"@metadata": {
    "beat": "filebeat",
    "type": "_doc",
    "version": "8.11.0"
},
"host": {
    "hostname": "aaaaaaaaaaaa",
    "architecture": "x86_64",
    "os": {
        "family": "debian",
        "name": "Ubuntu",
        "kernel": "5.10.102.1-microsoft-standard-WSL2",
        "codename": "focal",
        "type": "linux",
        "platform": "ubuntu",
        "version": "20.04.6 LTS (Focal Fossa)"
    },
    "containerized": true,
    "ip": [
        "1.1.1.1"
    ],
    "mac": [
        "00-00-00-00-00-00"
    ],
    "name": "aaaaaaaaaaaa"
},
"agent": {
    "ephemeral_id": "42aa9a31-f251-420f-9e2c-b1aaea30da4a",
    "id": "2fa6eee8-a5d3-40a5-8c2d-406ee3670369",
    "name": "aaaaaaaaaaaa",
    "type": "filebeat",
    "version": "8.11.0"
},
"ecs": {
    "version": "8.0.0"
},
"log": {
    "offset": 50,
    "file": {
        "path": "/logs.txt"
    }
},
"message": "{\"host\": \"123\"} ",
"input": {
    "type": "log"
}
}

"host" object value from message

{
"@timestamp": "2024-03-20T13:33:25.932Z",
"@metadata": {
    "beat": "filebeat",
    "type": "_doc",
    "version": "8.11.0"
},
"host": "123",
"agent": {
    "ephemeral_id": "42aa9a31-f251-420f-9e2c-b1aaea30da4a",
    "id": "2fa6eee8-a5d3-40a5-8c2d-406ee3670369",
    "name": "aaaaaaaaaaaa",
    "type": "filebeat",
    "version": "8.11.0"
},
"ecs": {
    "version": "8.0.0"
},
"log": {
    "offset": 50,
    "file": {
        "path": "/logs.txt"
    }
},
"message": "{\"host\": \"123\"} ",
"input": {
    "type": "log"
}
}