Upgrade to 11.4.5, a Webform with a file upload field loses file on submit for anonymous

Problem/Motivation

After upgrading Drupal Core from 11.4.4 to 11.4.5, anonymous users submitting a Webform with a file upload field experience an issue where the uploaded file is lost during form submission
The upload initially succeeds and a temporary file entity is created. During form validation, the file field contains the expected file ID (fid). However, by the time the form submit handler and hook_webform_submission_presave() execute, the file field value becomes empty. As a result:
• The Webform submission does not store the uploaded file.
• Email handlers do not receive the file attachment.
• The temporary file remains in the system but is not associated with the submission.
• The issue occurs only for anonymous users.
• Authenticated users are not affected.

Steps to reproduce

• Create a webform with file field, with file settings as private files(s3fs)
• Submit a webform with file upload field as anonymous user.
• Form submits successfully but file is removed from submission data.
• If file field is mandatory then form gives error "file field is mandatory".

Proposed resolution

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet