Reproduction steps:
1. Open the “IN-73972.zip” Project
2. Open the “MainTex” Shader in Assets > Shaders
3. Create a new Texture2D Property ( + > Texture2D in the Blackboard window)
4. Observe the Property’s Node Settings in the Graph Inspector

Expected result: The Reference is automatically set to “_MainTex”
Actual result: The Reference is set to “_Texture2D”

Reproducible with: 2021.3.37f1, 2022.3.26f1, 6000.0.0f1

Reproducible on: Windows 10 (by reporter), Windows 11
Not reproducible on: No other environment tested

Note:
- There is a lack of documentation saying that “_MainTex” is required for the texture to work correctly