403 error when viewing attachments as a Customer for Next-Gen projects

Summary

All attachments added by agents in next-gen service desk project tickets are failing to load for customers in the portal.

Steps to Reproduce

1. Create an issue on a Next-Gen Service Desk project.
2. As a Service Desk agent, edit the issue description or add a comment including an image attachment.
3. As a Customer, open the ticket on the portal.

Expected Results

All images are viewable.

Actual Results

Only image uploaded by the customer are viewable.

All images uploaded by agents show this error in the dev console
Encountered a "403 - Forbidden" error while loading this page.

Workaround

No workaround is available at this time.