Recently in the open beta, friend statuses become bugged for some reason when they leave an instance.

In the screenshot attached, a friend joined me for a bit and then got off vrchat. Their physical presence in the lobby disappeared as normal. But their name is still in the list of users in the world even after they have left. It even marks them as "offline". Seems to persist for as long as you are in the instance.

Started about a week ago I believe, but I may be wrong and it might be a bit longer.