Those users having continuous use and now report problems are likely not on the Responses endpoint.
The timeout error on internet URL has been fixed, confirmed locally, but base64 data URL still has the same “An error occurred while processing your request”.
Chat Completions and Responses on the API Playground are sending the same base64 encoding. One just fails. The same trying base64 locally.
The Playground is forming the request properly, otherwise the validation would bounce it:
Chat completions: "content":[{"type":"image_url","image_url":{"url":"data:image/png;base64,iVBORw0...
Responses: "content":[{"type":"input_image","image_url":"data:image/png;base64,iVBORw0KGgoAAAANSU...