Overview
I configured Strapi with the following plugin to store media in S3.
https://www.npmjs.com/package/@liashchynskyi/strapi-provider-upload-s3-cloudfront
At that time, the following error occurred and images were not displayed.
I was able to resolve this issue by modifying ./config/middleware.js, as described in the following article.
https://zenn.dev/studiobros/articles/04400f413eb2aa
Regarding ACL
Similarly, I also encountered a situation where media could not be uploaded to S3. However, as described in the above article, by enabling S3 ACL and configuring the appropriate Block Public Access (bucket settings), I was able to upload successfully.
Summary
I hope this serves as a useful reference for building a headless CMS combining Strapi and S3.