Reproduction steps:
1. Open the attached "ReproProj" project
2. Open "Assets/Scenes/OutdoorsScene" scene
3. In the Hierarchy window, expand the “Canvas” GameObject and click on the “Image” GameObject to open its' Inspector window
4. Change the preview to Default UI Material
5. Move the mouse around the Scene View or Game View and observe the results

Expected results: The Canvas does not flicker or change size
Actual results: The Canvas keeps changing size whenever the mouse is moved

Reproducible with: 2022.3.18f1, 2022.3.20f1
Not reproducible with: 2021.3.35f1, 2022.3.17f1, 2023.2.10f1, 2023.3.0b7

Reproducible on: Windows 11 Pro
Not reproducible on: No other environments tested

Notes:
- Not reproducible if only the Scene view and the Default UI Material preview are visible
- Reproducible when only the Game view and the Default UI Material preview are visible
- Reproducible with both Image and RawImage GameObjects