How to reproduce:
1. Open the user's attached project
2. Open scene Scenes/Bugs
3. Go to the Game view and enable the Stats overlay
4. Press the Play button and observe the number of Tris drawn
5. Press the Play button again to exit Play mode
6. In the Hierarchy window, select the GameObject "Planar Reflection"
7. Disable the GameObject by disabling the checkbox next to its name in the Inspector view
8. Press the Play button and observe the number of Tris drawn
Expected result: the number of triangles drawn is around 1.4M before and after disabling Planar Reflection
Actual result: the number of triangles drawn is around 3.6M before disabling Planar Reflection
Reproducible with: 10.8.1 (2020.3.27f1), 12.1.4 (2021.2.9f1), 13.1.5 (2022.1.0b5, 2022.2.0a2)
Could not test with: 7.7.1 (2019.4.35f1) (HDRenderPipelineAsset.CreatePipeline errors)