How to reproduce:
1. Create a new Unity project
2. Create and open any UXML (UI Document) in the UI Builder
3. Add a VisualElement to the Hierarchy and select it
4. In the Inspector, under Background, set the Image dropdown to "Gradient"
5. Click the Color field to open the Gradient Editor and add color/alpha keys until there are more than 4 unique key times (e.g. 7)
6. Drag one of the keys back and forth past the other keys
7. Observe the results and the Console
Expected results: The gradient preview updates smoothly and consistently as the key is dragged
Actual results: The gradient preview flickers and jumps between different renderings as the dragged key crosses other keys, and the Console repeats "Background gradient has 7 unique key times; only the first 4 are kept. Reduce the number of color/alpha keys to silence this warning."
Reproducible with: 6000.7.0a4, 6000.7.0b1
Can't test with: 6000.7.0a3 (No Gradient)
Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested
Note: UI Toolkit's background-image gradient hard-caps at 4 keys (separate from the core Gradient class's 8-key limit)