How to reproduce:
1. Open the attached project ("CommandBuffer CurrentActive Bug.zip")
2. Enter Play Mode
3. Select the "Test" GameObject in Hierarchy
4. Observe the preview of the RenderTexture in Inspector
5. Click "Toggle Secondary Camera" in the Inspector

Expected result: RenderTexture preview displays the RenderTexture
Actual result: RenderTexture preview displays a white texture

Reproducible with: 2021.2.5f1, 2022.1.0a16
Could not test with: 2019.4.33f1, 2020.3.23f1 ("Type of conditional expression cannot be determined because there is no implicit conversion between 'UnityEngine.RenderTexture' and 'UnityEngine.Texture2D'")

Note:
- This behavior does not occur under certain circumstances, although these are not the desired use cases:
- If the secondary camera's depth is less than the main camera's depth
- If the secondary camera's depth is greater than the main camera's depth and the secondary camera's viewport rect doesn't match the main camera's