I'm noticing the issue on static.spore.com when using HTTPS as well, however, it does not seem to affect all creations. A small number are fine.
For example, the current most recent featured creation works fine: https://static.spore.com/static/thumb/501/099/886/501099886802.png
But the second-most recent featured creation does not: https://static.spore.com/static/thumb/501/099/876/501099876776.png
The former works fine on both http and https, while the latter works fine on http but gives 503 "An error occurred while processing your request." on https.
Thinking it might be some caching/CDN issue. I've disabled browser cache (via devtools) to rule that out. Screenshot of devtools is attached.