Reproduction steps:
1. Download and open the attached project: "ShaderClipIssue-2021.2.zip"
2. Build and Run to a mobile device
3. Observe the running Player

Expected result: The dithering can clearly be observed
Actual result: The dithering is absent

Reproducible with: 7.7.1 (2019.4.32f1), 10.6.0 (2020.3.21f1), 11.0.0 (2021.1.27f1), 12.0.0 (2021.2.0b17), 13.1.0 (2022.1.0a13)

Reproduced on:
VLNQA00112, Htc M9 (HTC One M9), Android 7.0, CPU: Snapdragon 810 MSM8994, GPU: Adreno (TM) 430
VLNQA00025, Xiaomi Mi 5s (MI 5s), Android 6.0.1, CPU: Snapdragon 820 MSM8996, GPU: Adreno (TM) 530
VLNQA00391, Xiaomi Redmi 9A (M2006C3LG), Android 10, CPU: MediaTek Helio G25 (MT6762G), GPU: PowerVR Rogue GE8320
VLNQA00286, Meizu Pro 5 (PRO 5), Android 7.0, CPU: Exynos 7 Octa 7420, GPU: Mali-T760
VLNQA00313, Huawei Y6 Ⅱ Compact (HUAWEI LYO-L01), Android 5.1, CPU: MediaTek MT6735, GPU: Mali-T720
----------, Oneplus OnePlus 8 Pro (IN2023), Android 11, CPU: Snapdragon 865 SM8250, GPU: Adreno (TM) 650
----------, Samsung S21 (SM-G991U), Android 11, CPU: Snapdragon 888, GPU: Adreno (TM) 660
Reproduced with iPhone 12 Pro (iOS 14.2.1)

Did not reproduce on:
VLNQA00134, Samsung Galaxy S8 (SM-G950F), Android 9, CPU: Exynos 9 Octa 8895, GPU: Mali-G71
VLNQA00335, Samsung Galaxy S20+ 5G (SM-G986B), Android 10, CPU: Exynos 990, GPU: Mali-G77

Notes:
- There are screenshots attached below illustrating the reproduced and non-reproduced issue (Repro.png, NoRepro.png)
- Reproducible with either Vulkan or OpenGL Graphics API
- Not reproducible on desktop builds (Linux, macOS, Windows)
- Could not test with the Built-in Render Pipeline due to shader errors