I have this rule configured like so:

'import/extensions': ['error', 'ignorePackages'],

With this configuration, the following is flagged as an error:

import { Something } from './LocalFolderWithIndexfile'

However, the following is not flagged as an error, but I believe it should be:

import { Something } from '.'

The only difference between the two is where in the file tree the importing file sits. As a workaround, one can supplement this rule with the general no-restricted-imports rule like this:

'no-restricted-imports': ['error',
  {
    paths: [
      {
        name: '..',
        message: 'Import from ../index.js instead.',
      },
      {
        name: '.',
        message: 'Import from ./index.js instead.',
      },
    ],
  },
],

Apologies if this has already been filed. I found it really hard to search for