How to reproduce:
1. Open the “UIToolkitPerformance.zip“ project
2. Open the “TestScene“
3. Build and Run for Android (Development Build)
4. Connect the Profiler to the Device

Expected result: No large increase in the time consumption for the rendering process
Actual result: A large increase in the time consumption for the rendering process when adding background color and/or texture

Reproducible with: 2021.3.47f1, 2022.3.55f1, 6000.0.32f1, 6000.1.0a9

Reproducible environment: macOS 15.1.1 (Intel), Windows 11 (Reporters)
Not reproducible environment: No other environment tested

Reproducible with these devices:
VLNQA00178, Xiaomi Redmi Note 4 (Redmi Note 4), Android 6.0, CPU: MediaTek Helio X20 MT6797M, GPU: Mali-T880
VLNQA00107, Huawei Nexus 6P (Nexus 6P), Android 8.1.0, CPU: Snapdragon 810 MSM8994, GPU: Adreno (TM) 430

Not reproducible with these devices:
VLNQA00511, 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
VLNQA00518, Google Pixel 4 (Pixel 4), Android 13, CPU: Snapdragon 855 SM8150, GPU: Adreno (TM) 640
VLNQA00152, Huawei P9 (EVA-L19), Android 7.0, CPU: HiSilicon Kirin 955, GPU: Mali-T880
VLNQA00535, iPhone XS (MT9F2ET/A), CPU: Apple A12 Bionic, GPU: Apple designed, OS: 17.6.1
VLNQA00600, iPad Pro (9.7 inch, WiFi), CPU: Apple A9X, GPU: Apple designed, OS: 14.8

Notes:

Not reproducible in the Editor or Standalone
Reproducible with both OpenGLES3 and Vulkan Graphic API
The reporter pointed out that the issue is coming from the “UnityUIE.cginc“ file, where the extensive branching (particularly when selecting texture) creates performance issues on some older Android devices
More information in the comments