We have reports of 403 Forbidden errors when using an Ayrshare hosted media URL - images.ayrshare.com and img.ayrshare.com. The issue seems to be with Google (storage provider) having server issues. We have reported this to Google and are awaiting their investigation.
In the meantime, we have included a retryAvailable: true return when a 403 Forbidden error is returned. When this field is present, you can retry the post and is should successfully be published.