View the original community article here
Last tested: Dec 11, 2017
If you come across an unexpected bin filter on an automagic heatmaps, this is expected behaviour. These filters are not coded in LookML or any other section of Looker so are not searchable.
The filter value there is the "binning resolution" of how granular the heatmap squares are. The map automatically determines the best choice for the current map view.