Tooltip is missing for Add () button in Particle system.

In the particle system, under the Renderer parameter, for Mesh Render mode, the Tooltip for Add () button is missing in the inspector window. Refer attached screenshot.

Steps to repro:
1. Create a New Project.
2. Hierarchy > Effects > Particle system.
3. Particle System > Inspector > Renderer > Render Mode > Mesh
6.Observe tooltip is missing for Add () button

Actual result:
Tooltip is missing for Add Mesh () button

Expected result:
Tooltip appears when the mouse has hovered on the properties

Reproducible in:
2021.2.0a16, 2021.1.6f1, 2020.3.7f1, 2019.4.25f1, 2018.4.34f1

Note: Tooltip appears for similar add (+) button in Game View tab for free aspect add button

Environment:
Occurring on Mac 11.2.3 and windows 10