What you saw is the generic way of displaying RSS feeds. Since we allow arbititrary feeds to be added to rooms (e.g. someone's blog), the default way of rendering that into chat just uses the information commonly included in RSS feeds (title, name of author, date, excerpt).
If, however, the RSS item's link is something that chat can onebox, it will do that: Instead of displaying the information as it is in the RSS feed, it does whatever magic is involved for oneboxing that link, and displays the onebox instead. This doesn't only work for Stack Exchange questions, but also e.g. for the XKCD feed or a Twitter user's RSS feed.
If the RSS item doesn't have a oneboxable link, or if (for whatever reason) the data necessary to show the onebox isn't available, the default layout will be used.
As you noticed, oneboxing of questions was unavailable for short moment (a temporary glitch in our API), so chat fell back to displaying the regular RSS feed contents in the default layout. This is intentional;
unlike when you post a link into chat (in which case all we have is a link), we have at least some information when the data comes from a feed, so it's better to use that than nothing at all.