Reproduction steps:
1. Open the user's attached project "JitterReproduction.rar"
2. In the Project window open "SampleScene.unity" under "Scenes" folder
3. Go to "HDRPDefaultResources" folder and select "HDRenderPipelineAsset.asset"
4. In the Inspector window make sure that Motion Vectors is disabled and Lit Shader Mode is set as Foward Only and MSAA is Enabled (2x, 4x or 8x)
5. Enter Play Mode

Expected result: disabling Motion Vectors and enabling MSAA does not leave a texture watermark in the Game View
Actual result: disabling Motion Vectors and enabling MSAA leaves a texture watermark in the Game View (See attached MotionVectorsOff.mp4)

Reproduces on: HDRP 7.3.1 (2019.3.16f1, 2019.4.0f1)
Does not reproduce on: HDRP 8.1.0 (2020.1.0b10, 2020.2.0a13)
Could not test on 2018.4.23f1 due to the project breaking

Notes:
-When Motion Vectors is disabled and MSAA is enabled there is a black watermark with a texture which seems to be the initial state of the first frame blending with the final render