Thanks for your feedback. A “normal” upload to my Cloudinary account (not via Strapi) works fine.
401 is, what gets returned, when uploading from my localhost Strapi installation, and 503, when uploading from heroku, as mentioned. All that with Strapi 4.0.5 and 4.0.6.
Does your Strapi 4 version work with the cloudinary provider plugin. @Eventyret ?