Encrypted file URL's return a 404 on D11

Problem/Motivation

When I use this module to upload a file from a webform, I cannot seem to download it using the created download URL. The PathProcessor doesn't seem to attach the 'file' query parameter, resulting in a 404 on Drupal 11.

Steps to reproduce

1. On Drupal 11, upload an encrypted file.
2. Try downloading the file using the /encrypt/files/{filepath} route.
3. A 404 is served.

Proposed resolution

Remove the leading backslashes in the services file, so the path processor is hit again. Ensuring that the 'file' query parameter is set.

Remaining tasks

None

User interface changes

None

API changes

None

Data model changes

None