Steps to reproduce:

1. Create a new 3D URP project
2. Drag the attached "Gradient.cs" script into the Project window
3. In the Hierarchy, create a new GameObject and drag the script onto it
4. Select the created GameObject
5. In the Inspector, click on the Gradient field
6. Press "Ctrl+Z"
7. Observe the Console

Actual results: "InvalidOperationException: Collection was modified; enumeration operation may not execute." error is thrown

Expected results: No Console errors are thrown 

Reproducible with versions: 6000.0.49f1, 6000.0.75f1, 6000.3.15f1, 6000.4.7f1, 6000.5.0b8, 6000.6.0a4

Not reproducible with versions: 6000.0.48f1

Tested on (OS): Windows 11, macOS 26.4

Error:
{code:java}
InvalidOperationException: Collection was modified; enumeration operation may not execute.
System.Collections.Generic.List`1+Enumerator[T].MoveNextRare () (at <4ea9c5843f6c401888efb0bdc93eda21>:0)
System.Collections.Generic.List`1+Enumerator[T].MoveNext () (at <4ea9c5843f6c401888efb0bdc93eda21>:0)
UnityEditor.InspectorWindow.RedrawFromNative () (at <b684b671bbe94fa7880860517fcd126d>:0)
UnityEditor.EditorApplication:Internal_CallGlobalEventHandler(){code}