Title not being removed from excerpt for any collection other than posts

[staticintlucas]

Describe the bug

With strip_title: true, post.excerpt has the title removed as expected. For any other type of collection, for example books, book.excerpt will still contain the title.

Steps to reproduce the behavior

Create a Jekyll project with a collection other than post. e.g.:

collections:
  books:
    output: true

Expected behavior

Title should be removed from the collection

Screenshots

N/A

Additional context

N/A