Reproduction steps:
1. Create a new project
2. Import "MyCollider.cs"
3. Create a Prefab and attach the "MyCollider.cs" Script to it
4. Select the Prefab in Project Window and inspect the Console

Expected result: OnEnable is called once
Actual result: OnEnable is called every frame when the Prefab is selected

Reproducible with: 2018.4.22f1, 2019.3.14f1, 2020.1.0a8, 2020.1.0b8, 2020.2.0a10
Not reproducible with 2017.4.40f1, 2019.2.21f1, 2019.3.0b1, 2020.1.0a7

Notes:
1. Sometimes (earlier versions) OnEnable() only gets called when Object is selected in Hierarchy and doesn't work in the Project Window which makes it impossible to reproduce the issue since it only reproduces in Project window
2. The issue has been backported to 2018.4, 2019.3
3. Video of the issue is attached