Reproduction steps:
1. Open the attached “CanvasScaling.zip” project
2. Open “SampleScene”
3. Click on several GameObjects in the Hierarchy window
4. Observe the Scene window

Expected result: Nothing of note happens
Actual result: Canvas GameObject size changes

Reproducible with: 2022.3.18f1, 2022.3.20f1
Not reproducible with: 2022.3.17f1, 2023.2.12f1, 2023.3.0b9
Could not test with: 2021.3.35f1 (due to Canvas GameObject not rendering)
Fixed in: 2022.3.21f1

Notes:
- Game window flickers as Canvas GameObject changes its size
- Reporter noted that having the Game View undocked or next to the Scene View reduces but does not remove the problem