The documentation for npm ls highlights that significant changes to the command might be comming with version 8.

https://docs.npmjs.com/cli/commands/npm-ls

A thorough re-examination of the use cases, intention, behavior, and output of this command, is currently underway. Expect significant changes to at least the default human-readable npm ls output in npm v8.

This is either obsolete or the version should be increased to the next one.