Reproduction steps:
1. Open the attached “BugRepro” project
2. Open the “SampleScene” Scene
3. Select the “Main Camera” GameObject in the Hierarchy window
4. Make sure “Volume Blending Layer” is set to “B” under “Post-process Layer” component
5. Set the “Cube” GameObject Layer to “B”
6. Set the “Cube (1)” GameObject Layer to “A”
7. Observe the Scene / Game View

Expected result: Only the “Cube” GameObject has the “Bloom” effect
Actual result: Both “Cube” and “Cube (1)” GameObjects have the “Bloom” effect

Reproducible with: 3.4.0 (2021.3.41f1, 2022.3.40f1, 6000.0.13f1)

Reproducible on: Windows 10
Not reproducible on: No other environment tested