With Bountysource (the platform I used), there is. IIRC, they will also post a comment on the issue, listing the current bounty, and optionally also automatical

With Bountysource (the platform I used), there is. IIRC, they will also post a comment on the issue, listing the current bounty, and optionally also automatically apply appropriate labels to issues, so it's obvious to anyone on the Github issue. Most of the solutions proposed in this thread for one-off bounties here have already been implemented for years, which is why I am convinced that (with the current level of funding), bounties don't work.