Reproduction steps:
1. Open the attached project “DecalEmissionBug”
2. Select the “Main” scene
3. Split Scene view and Game view into two separate windows
4. Select “Main Camera” GameObject
5. In Inspector, under the “Camera” component, change the “Clipping Planes” property values
6. Observe emission on the “Cube” GameObject
7. Experiment with more “Clipping Planes” property values

Expected result: One side of the “Cube” GameObject is always bright red
Actual result: The shape of the emission on the “Cube” GameObject changes

Reproducible with: 2020.3.44f1, 2021.3.16f1, 2022.2.2f1, 2023.1.0a25, 2023.2.0a3

Reproducible on: Windows 10

Notes:
When modifying “Clipping Planes” property values, it is advisable to change “Near” by adding 0.01 and “Far” by adding 100 for better visual results. Also, moving the “Main Camera” GameObject in Z-Axis will provide the same results.
In the 2020 versions, need to modify the Decal Projector boundaries to the shape of a cube on the “Decal” GameObject