Hi I had this reply from Airtable Support.
You mentioned that these URLs are from Google Drive. Currently, there is a known issue with Google Drive where these requests are rate-limited, causing some uploads to fail. Our team has thoroughly looked into this issue – unfortunately, the scope of work required for resolving this issue is quite significant, and we do not at this time have a concrete timeline for when this will be resolved. I’m really sorry about this.
If you are able to move your files to another file service, such as Dropbox, then the issues you are seeing with failed uploads should be eliminated.
Apologies for this limitation at the moment. Please let me know if there’s anything else I can help clear up!
So doesn’t look like anything is going work soon!