Cross-layer symbol collision detection not working on iOS

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On Mapbox GL JS, symbol collision detection works globally across all symbol layers - icons from different layers don't overlap with each other.

On Mapbox Maps SDK for iOS v10, collision detection only works within individual layers. Icons from the same layer don't overlap, but icons from different layers can overlap.

**Environment:**
- Mapbox Maps SDK for iOS v10.19.2
- iOS 26

**Setup:**
- Multiple symbol layers with different sources (GeoJSON and vector tile sources)

**Question:**
Is cross-layer collision detection supported in iOS SDK v10, or is this a known platform difference? If it's not supported, is there a recommended approach for preventing symbol overlap across layers when using different source types?

I cannot combine layers into a single source because I need different source types and independent visibility control per layer.

Start by investigating cross-layer symbol collision behavior in Mapbox Maps SDK for iOS v10.19.2 with multiple symbol layers using GeoJSON and vector tile sources. Determine whether collision detection across layers is supported and document a recommended approach for preventing overlap while retaining independent visibility control.

Written by the indexing model from the issue text.