We use community events to promote new blog posts. Because we've had a lot of activity lately (yay!), we're sometimes showing three events at a time. (I run each event for around a week, so there's usually a little overlap with the oldest post when we post a new one.) Because the URLs need to be different, I'm using the full URL for the question for the newest one, and the answer link with and without my user ID for the other two. That's been working fine (the per-user share link actually counts as different).
On main, one of our events is being bumped by an SE-wide announcement. That's expected behavior, but what's not expected is which one got bumped. Here's what we see on main:
And here's what we see on meta, with the missing one circled:
Why, on main, did the system omit the one in the middle chronologically? I would have expected the oldest one to drop off. Shouldn't newer events have priority? (I realize that "oldest" and "expiring soonest" aren't the same thing, and working out the correct behavior means figuring out which we mean. On this site, they are usually the same -- we don't queue up events well in advance or run a bunch of newer, shorter ones.)
It's not about recency of editing, either. When I post a new event I first edit the previously-newest one to change its URL, and then post the new one with the question URL (that the previous one had until my edit). So the newest two events are also the most-recently-edited two events.