After upgrading from Theia 1.23 to Theia 1.57, VSCode plugins aren't loading anymore

[drochgenius]

Problem

I am getting the following error on Theia startup:

(...)
2025-01-24T21:16:56.745Z root INFO Configuration directory URI: 'file:///root/.theia'
2025-01-24T21:16:56.747Z root INFO Theia app listening on http://127.0.0.1:3000.
2025-01-24T21:16:56.748Z root WARN The local plugin referenced by local-dir:/root/.theia/plugins does not exist.
2025-01-24T21:16:56.748Z root WARN The local plugin referenced by local-dir:/root/.theia/deployedPlugins does not exist.
2025-01-24T21:16:56.751Z root WARN Only user plugins will be handled by file handlers, please unpack the plugin 'plankton-studio-plugin.vsix' manually.

I am launching Theia with the Theia CLI specifying a custom folder where my plugins (VSIX) packages are located.

theia start --plugins=local-dir:./plugins

I am not sure what it means
Only user plugins will be handled by file handlers, please unpack the plugin.

Do I need to unzip the plugin in the folder ./plugins ?

Context information

I am on MacOS, Node 20.
I am using Theia 1.57 for the web, with the following dependencies:

    "dependencies": {
        "@theia/core": "1.57.0",
        "@theia/monaco": "1.57.0",
        "@theia/plugin-ext": "1.57.0",
        "@theia/plugin-ext-vscode": "1.57.0"
    },
    "devDependencies": {
        "@theia/cli": "1.57.0",
        "node-gyp": "^11.0.0",
        "react": "^18.2.0",
        "react-dom": "^18.2.0"
    },

[msujew]

Hey @drochgenius,

we disabled support for builtins via .vsix back in #13435 (v1.49.0) to fix #13222 where builtins were showing up as user-installed plugins. As the warning suggests, please unpack the plugins to make them work as expected. You can just unzip the .vsix files.