It seems like experimental.min.css from unpkg.com has a bug with the Spinner.
We updated our Confluence cloud app, Approvals, with new AUI files. From 5.10.1 (aui-cdn) to 7.8.0 (unpckg) and we realised that the new spinner instead of spinning, it moved side to side.
In works correctly using the non-minified version. We downloaded that version, minified it and hosted ourselves, and that works fine as well.
Thanks and Regards,