referencesFeatureData

True when this expression (or any sub-expression) reads per-feature data — i.e. its result can differ between two features in the same tile at the same zoom. That means a reference to a feature property (Get / Has), the feature's dynamic state (FeatureState), its geometry type (GeometryType), or its line-progress parameter (LineProgress).

Constant literals and ["zoom"]-driven interpolations are NOT feature-dependent: within one tile zoom is constant, so a zoom-only expression evaluates identically for every feature. Walked once at style-build time (cached in MvtStyleRule.PaintSpec); the per- tile paint cache reuses one resolved result across all features matching a clean rule.