Hello @meryldelpech,
Thanks for sharing your issue and welcome to our community 
I am not an expert of Rails Active Storage, can you tell me where the images are actually saved? On a server like Amazon S3 for instance?
If they are stored in an external cloud, you’ll need to refer to the image links to display them (and you can use prefix as specified here).
Be aware that, as explained here:
Your images need to be public to be displayed.
If you must keep them private , you should consider using signed URLs.
Let me know if that helps.