Reproduction steps:
1. Open the attached “IN-101523.zip” project
2. Open the “SampleScene”
3. Go to Edit > Preferences > Color
4. Find the “Playmode tint” property under General tab
5. Change it to any brighter color so the issue is more apparent (e.g. Red)
6. Enter Play mode
7. Click on the “Test” GameObject in the Hierarchy
8. Observe the color fields in the “Test (Script)” Component in the Inspector

Expected result: The “Playmode tint” does not affect color fields
Actual result: The “Playmode tint” affects both color fields ('color' and ‘gradient’ fields)

Reproducible with: 2023.1.0a3, 6000.0.48f1, 6000.1.3f1, 6000.2.0b1
Not reproducible with: 2022.3.62f1, 2023.1.0a2

Reproducible on: Windows 10 (User reported), Windows 11
Not reproducible on: no other environment tested

Note:
- Probably caused by using the new UIToolkit Inspector. When "Use IMGUI Default Inspector" is set to true in Edit > Project Settings > Editor, both fields are behave correctly