On decreasing the width of the Search window from Preferences, 'typing debounce threshold(ms)' horizontal scrollbar getting disappears. refer to the attached video.

Steps to repro:
1. Create a new project
2. Unity > Preferences > Search
3. Decrease the width of the Search window

Actual Result:
'Typing debounce threshold(ms)' horizontal scrollbar disappears on decreasing the width of the Search window

Expected Result:
'Typing debounce threshold(ms)' horizontal scrollbar should display gracefully

Occurring on:
2021.1.0a1,
2020.2.0b7 with Quick Search Package Version 3.0.0-preview.1

Working Fine:
2020.2.0b7 with Quick Search 2.1.0-preview.4

Note: Quick Search is a Built-In Package in the Unity 2021.1.0a1

Environment:
Occurring on Windows 10 & macOS 10.15.