Hi!
It does use Google-related URLs.
Could you send an e-mail to support@itch.io with the following:
- The output of `butler push -v ...` - the "-v" is important here, the "..." are just what you would normally pass butler
- The country you're uploading from
Thanks!
Update: the panic itself was a bug (now fixed in master), but yep, China does block Google Cloud Storage.