Reproduction steps:
1. Create a new project
2. Create UI Document (Create > UI Toolkit > UI Document)
3. Double-click newly created Asset to open UI Builder window
4. Click on “NewUXMLTemplate.uxml”
5. Enable Editor Extension Authoring
6. Drag Gradient Element to the Hierarchy and select it
7. Click on the Value field to open Gradient Editor (Inspector > Attributes > Value)
8. Observe the gradient markers

Actual result: Bottom-right gradient marker is green
Expected result: Bottom-right gradient marker is blue

Reproducible with: 6000.0.60f1, 6000.2.8f1, 6000.3.0b6, 6000.4.0a2
Couldn’t reproduce with: 2021.3.57f1, 2022.3.67f1 (No gradient field)

Reproduced on: Windows 11, macOS Sequoia 15.4 (M4)

Note: Color turns blue after clicking on the marker