How to reproduce:
1. Open the attached project's Scene labeled "Bug"
2. In the Hierarchy, select the "BadStyle" GameObject
3. In the Inspector, preview the drawn buttons
4. Inspect the middle "B" button between "A" and "C"
Expected result: Spacing between buttons is equally distributed
Actual result: Button's with EditorStyles.miniButtonMid style margins are offset slightly
Reproducible with: 2019.3.9f1, 2019.4.29f1, 2020.3.16f1, 2021.1.17f1, 2021.2.0b7, 2022.1.0a5
Not reproducible with: 2019.3.8f1