Reproduction steps:
1. Open the attached “Repro” project
2. Open the “Assets/PostSharpenTAA.unity” Scene
3. Enter the Play Mode and Observe the Game View
4. Select the “Camera” GameObject in the Hierarchy window
5. Change the “Sharpening Mode” to “Post Sharpen” located in the “Camera” Component’s Rendering section
6. Observe the Game View

Expected result: The colors are sharp and accurate
Actual result: The colors are washed out

Reproducible with: 2023.1.7f1, 2023.2.0b3
Couldn’t test with: 2021.3.29f1, 2022.3.6f1 (“Sharpening Mode” option is not present)

Reproducible on: Windows 10 Pro (22H2)

Note: This issue occurs only when both the Rendering “Color Buffer Format” and Post-processing’s “Buffer Format” are simultaneously set to “R16G16B16A16” in the active HDRP asset