Reproduction steps:
1. Open the attached “MotionVectorTest.zip” project
2. Open the “Assets/OutdoorsScene.unity“ Scene
3. Make sure that the Main Camera has the Post Processing enabled and anti-aliasing set to “Temporal Anti Aliasing (TAA)”
4. Enter the Play Mode
5. Open the Rendering Debugger (Window > Analysis > Rendering Debugger)
6. In Rendering Debugger, set the Map Overlays to “Motion Vector (100x, normalized)” (Rendering > Map Overlays)
7. Observe the Game view top right corner

Expected result: Both cubes should display correct motion vectors
Actual result: The left cube correctly displays motion vectors and the right cube appears black

Reproducible with: 6000.0.38f1, 6000.1.0b6, 6000.2.0a4
Couldn't test with: 2022.3.58f1 (There is no Motion Vector (100x, normalized))

Reproducible on: Windows 11
Not reproducible on: No other environment tested