precisionRadiusMetersOrNull

Radius, in metres, of the uncertainty circle a firmware precision_bits implies, or null when the position is not degraded.

The nullability is the point. This lived in three places — a lookup table on the Google map's cluster item, an identical one in the MapLibre map, and a 23905787.925008 * 0.5^bits formula in the precision preference — and only the tables answered "not degraded" at all. The formula returns a number for every input, so the callers that used it guarded with > 0, which is true for the whole range: an undegraded position asked the node-detail mini-map for a circle roughly 23,905 km across, and asked the compass for one 5 mm across.

The table and the formula agreed to within 1.1 cm at every depth, so this keeps the tabulated values the maps have always drawn.