The Package Name, Version, and Description in the Package Manager Window allows editing the text like 'Cut', 'Copy' & 'Paste'.
Refer to the attached Video.

Steps to Reproduce:
1. Create a New Project
2. Window > Package Manager > Select
3. Package Manager Window >Any Package > Name/Version/Description > Select
4. Enter or paste any text

Actual Result:
Package Details are editable

Expected Result:
Package Name, Version, and description should not allow editing except "Copy"

Occurring on:
2021.1.0a8

Working Fine on:
2021.1.0a7, 2020.2.0b14

Environment:
Windows 10 and macOS 10.14, 10.15