"Objects are trying to be loaded during a domain backup" errors thrown in Console when switching Editor Theme with Shader Graphs containing Sample Texture 2D Nodes open

Steps to reproduce:
1. Create new Unity project using Universal 3D Template
2. Open Package Manager window
3. Navigate to Shader Graph > Samples and import the Node Reference sample
4. Open Assets > Samples > Shader Graph > 17.6.0 > Node Reference > Channel > “Flip” shader graph (double-click)
5. Open Assets > Samples > Shader Graph > 17.6.0 > Node Reference > Channel > “Split” shader graph (double-click)
6. Open Edit > Preferences > General
7. Change Editor Theme from Light to Dark
8. Change Editor Theme from Dark to Light
9. Observe the Console window

Actual results:  Multiple "Objects are trying to be loaded during a domain backup. This is not allowed as it will lead to undefined behaviour!" errors are thrown in the Console, one per Texture2D property with an assigned texture across all open Shader Graph windows

Expected results: No errors are thrown in the Console window

Reproducible with versions: 6000.0.76f1, 6000.3.17f1, 6000.4.10f1, 6000.5.0b11, 6000.6.0a6

Tested on (OS): Ubuntu 24.04, macOS Tahoe 26.4.1

Notes:

•  The errors also reproduces when switching Dark → Light → Dark

Objects are trying to be loaded during a domain backup. This is not allowed as it will lead to undefined behaviour!

UnityEditor.Graphing.GraphObject:OnBeforeSerialize ()