Error importing bootstrap's minified file: property "url" must be followed by a ':'

[afialapis]

Having this import in my code:

@import '~bootstrap/dist/css/bootstrap.min.css';

produces this error:

  Error: property "url" must be followed by a ':'
      at options.error (.../test-rollup-postcss-and-bootstrap/node_modules/node-sass/lib/index.js:290:33) {
    status: 1,
    file: '.../test-rollup-postcss-and-bootstrap/node_modules/bootstrap/dist/css/bootstrap.min.css',
    line: 6,
    column: 69384,
    formatted: `Error: property "url" must be followed by a ':'\n` +
      '        on line 6 of node_modules/bootstrap/dist/css/bootstrap.min.css\n' +
      '        from line 1 of src/style.scss\n' +
      '>> size:1.25rem;--bs-navbar-toggler-icon-bg:url("data:image/svg+xml,%3csvg x\n' +
      '   ------------------------------------------^\n',
    code: 'PLUGIN_ERROR',
    plugin: 'postcss',
    hook: 'transform',
    id: '.../test-rollup-postcss-and-bootstrap/src/style.scss',
    watchFiles: [
      '.../test-rollup-postcss-and-bootstrap/src/index.js',
      '.../test-rollup-postcss-and-bootstrap/src/style.scss'
    ]
  }

The error does not appear if we import he unminified file, like:

@import '~bootstrap/dist/css/bootstrap.css';

I have prepared the repo test-rollup-postcss-and-bootstrap to test this.

Running postcss (and node-sass) on their own does not seem to produce the problem.

This is the related css failing (of the unminified file, node_modules/bootstrap/dist/css/bootstrap.css):

.navbar {
...
  --bs-navbar-toggler-icon-bg: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba%280, 0, 0, 0.55%29' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");

Error happens, at least, on this bootstrap versions:
· 5.1.3
· 5.2.2

Am I missing some param to rollup-plugin-postcss?

Thanks!