How to reproduce:
1. Create a new project and add the TextMeshPro package
2. Create a "TextMeshPro - Text" GameObject via Create > 3D object > TextMeshPro - Text
3. Select the GameObject and observe attached components in the Inspector window

Expected result: the prefab's Canvas Renderer component is not hidden
Actual result: the prefab's Canvas Renderer component is hidden

Reproducible with:
TMP 0.1.2 (2018.4.10f1, 2019.2.8f1, 2019.3.0b6, 2020.1.0a8)
TMP 1.2.2 (2017.4.32f1)
TMP 1.4.1 (2018.4.10f1)
TMP 1.5.0 (2018.4.10f1)
TMP 2.0.1 (2019.2.8f1, 2019.3.0b6, 2020.1.0a8)

Note: creating a prefab from the GameObject and vice versa makes the component visible