Extension config inside devcontainer.json is ignored

I have this in my .devcontainer/devcontainer.json:

{
    "name": "test",
    "build": {
        "dockerfile": "Dockerfile",
        "context": ".."
    },
    "customizations": {
        "vscode": {
            "settings": {
                "yaml.format.enable": true,
                "yaml.schemas": {
                    "./my_schema.json": "*.yaml",
                },
                "yaml.maxItemsComputed": 80001
            },
            "extensions": [
                "redhat.vscode-yaml"
            ]
        }
    }
}

This does not work. When the dev container launches non of those settings are applied. I have to put those settings in a .vscode/settings.json file for the extension to use them.

I have not seen this with other extensions before, they all seem to pick up settings defined in devcontainer.json without issues.

Reproduce the report using the shown .devcontainer/devcontainer.json and compare the extension behavior with settings in .vscode/settings.json. Trace how the YAML extension receives settings when launched in a dev container; done means the listed YAML settings are applied from devcontainer.json, including the schema, formatting, and item limit.