I stumbled upon the following question When do you use brace expansion?
The second scoring answer got a bounty awarded by Community. How and why does such a thing happen? I did not see it before.
The FAQ states
If you do not award your bounty within 7 days (plus the grace period), > the highest voted answer created after the bounty started with at least 2 upvotes will be awarded half the bounty amount. If there's no answer meeting that criteria, the bounty is not awarded to anyone.
Apparently, then the bounty is awarded by Community, instead of by the user offering the bounty in the first place.