Tell us about your environment

• ESLint Version: 6.4.0
• Node Version: 12.10.0
• npm Version: 6.11.3

What parser (default, Babel-ESLint, etc.) are you using?

Default.

Please show your full configuration:
What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.

Online Demo.

/*eslint multiline-comment-style: [error] */

/*
{
    "foo": 1,
    "bar": 2
}
*/

What did you expect to happen?

ESLint fixes it to:

/*eslint multiline-comment-style: [error] */

/*
 * {
 *     "foo": 1,
 *     "bar": 2
 * }
 */

What actually happened? Please include the actual, raw output from ESLint.

ESLint fixed it to:

/*eslint multiline-comment-style: [error] */

/*
 * {
 * "foo": 1,
 * "bar": 2
 * }
 */

The indentation in the comment is broken.

Are you willing to submit a pull request to fix this bug?

Yes.