Observed at: https://stackoverflow.com/
This issue is present even after a hard refresh.
Additional Examples:
Communities:
Update:
On https://stackoverflow.com/ (not working) my sprites are loaded from https://cdn.sstatic.net/img/favicons-sprite16.png?v=57f32c762460
On https://meta.stackexchange.com/ (working) my sprites are loaded from https://meta.stackexchange.com/content/img/favicons-sprite16.png?v=57f32c762460
?v=57f32c762460
which I'd've assumed meant version and was meant to avoid caching issues.