change old query syntax:
{path}.vue?{ type: string, index?: number }#.{lang}

to:
{path}.vue.{lang}?rollup_plugin_vue={ type: string, lang: string, index?: number }

Plugins, like rollup-plugin-postcss also uses query params
for itself purpose, in this case if we provide { css: false } as options
to rollup-plugin-vue then we will get error from rollup, because
postcss can not recognize file ".vue?{...}#.css" as css file
and rollup-plugin-vue done its work also.

Rollup config where vue + postcss is not work:

export default [
  {
    input: '...',
    output: [
      {
        file: '...',
        format: 'es'
      }
    ],
    plugins: [
      // ...
      vue({
        css: false,
      }),
      postcss()
    ]
  }
];