Passing clean-css options doesn't work

Start by reproducing the Ember CLI project build with --environment production and trace how the minifyCSS options are passed to clean-css. Compare the nested level configuration with the clean-css optimization documentation; done means the build honors the requested per-optimization settings and the resulting CSS reflects them.

We recently updated all the packages and dependencies in our Ember.js project to their latest versions. Since then when this project is built with the --environment production flag, the CSS looks broken when browsing through its web pages. Disabling the CSS minifying fixes the issue.

I am trying to investigate and find out which CSS optimization is breaking our CSS styles, but it doesn't look like passing custom clean-css options is working correctly:

enabled works:

minifyCSS: {
      enabled: true // or false
}

level (integer) works:

minifyCSS: {
    options: {
        level: 1 // 0, 1 or 2
    }
}

level (with options) doesn't work:

minifyCSS: {
      options: {
        level: {
          1: {
            all: false,
            optimizeFont: true
          },
          2: {
            all: false
          }
        }
      }
    }

Passing the last options above does not have the desired result, which would be to only have optimizeFont enabled and all other optimizations disabled. The final CSS minifying looks the same as if everything was enabled.

The clean-css documentation says that we should be able to individually enable or disable each optimization (https://github.com/clean-css/clean-css?tab=readme-ov-file#level-0-optimizations) but I haven't encountered a single example of such a thing being done in Ember.js or in ember-cli-clean-css.