It seems like avatars used to be stored Atlassian CDN. Is it possible that the host is down now?
For example, this URL https://thepluginpeople.atlassian.net/secure/useravatar?avatarId=19725 redirects to https://avatar-cdn.atlassian.com/default that cannot be reached.
i randomly stumbled across AUI-CDN last night (funny that) and I also found it not functional in any way.
@sfbehnke There is a bug filed here: https://jira.atlassian.com/browse/JRACLOUD-74059
Looks as if a fix has been made, but it’s still not fully rolled out. So, track that issue there, and we’ll reach out to the prod/eng team to get more details on ETA.