Time.deltaTime reports high variance and incorrect frame intervals on Meta Quest 3 when using Vulkan with OpenXR

How to reproduce:

1. Open the attached project “IN-138156”
2. Switch Build Target to Android and ensure Vulkan is the active Graphics API
3. Ensure OpenXR is configured for Meta Quest under XR Plug-in Management
4. Build and deploy to a Meta Quest 3
5. Wait several seconds for startup frame settling
6. Observe the on-screen deltaTime metrics and variance percentage

Actual result: Time.deltaTime shows 25%+ variance
Expected result: Time.deltaTime shows 15% or lower variance (Based on GLES)

Reproducible with: 1.10.0 (6000.0.2f1), 1.17.0-pre.2 (6000.0.71f1, 6000.3.11f1, 6000.4.0b12, 6000.5.0a9)

Reproducible on: Windows 11
Not reproducible on: No other environments tested

Reproducible on devices:
Meta Quest 2 (Quest 2), CPU: Snapdragon XR2, GPU: Adreno 650
Meta Quest 3 (Quest 3), CPU: Snapdragon XR2 Gen 2 (SM8550), GPU: Adreno (TM) 740

Notes:

• Time.time and other Time APIs exhibit the same incorrect behavior
• Reproducible in Editor with higher variance