Reproduction steps:
1. Open the attached project “TestPlanar”
2. Open the “Assets/Scenes/SampleScene.unity” scene
3. In the Hierarchy Window, tick the check-box on “New Sub Scene”
4. Enter Play Mode
5. Observe the Game View

Expected result: Both mirrors show reflections of the car
Actual result: Only the right mirror shows reflections of the car

Reproducible with: 1.0.10, 1.1.0-pre.3 (2022.3.0f1), 1.2.0-pre.6(2022.3.17f1, 2023.2.6f1, 2023.3.0b3)

Reproducible on: macOS(Intel) 14.2.1, macOS(M1 Max) (by user)
Not Reproducible on: No other environment tested

Note: GameObject rendering of the reflections is correct