In testing, we observed that aarch64 cloud instances running in an Openstack instance would hang occasionally, often during disk-intensive operations like software compilation. We observed this on a specific public Openstack cloud (Vexxhost), but cannot be sure whether it is somehow specific to that environment or may also affect others. We did not yet encounter the issue in testing on Amazon EC2.
This issue appears to happen only with btrfs storage, which is the new default in Fedora 35.
Bugzilla report: #2011928
There is no known workaround at present aside from somehow deploying with a different filesystem (which is beyond the scope of this document), but a fix has been proposed by an upstream developer and is showing promising results in testing so far. We hope to be able to include that fix in updated images in the near future.