How to reproduce:
1. Create a new empty project
2. Change External Script Editor to Visual Studio for Mac (Unity -> Preferences -> External Tools)
3. Turn on "Registry Packages" and "Built-in Packages"
4. Press "Regenerate project files"
5. Create a new C# script and open it
6. Build the script (Build -> Build All)
7. Open the Errors window (Bottom Right of the Window)

Expected results: No errors or warnings
Actual results: TMP_FontAsset.cs, TMP_FontAssetCreatorWindow.cs and UwpPlatformSetup.cs has "Obsolete" code

Reproducible with: 3.0.6 (2021.2.0a10, 2021.2.8f1)
Not reproducible with: 2.1.6 (2019.4.34f1), 3.0.5 (2020.3.25f1, 2021.2.8f1), 3.0.6 (2020.3.25f1, 2021.2.0a9, 2022.1.0b2)

Note:
- It would seem that after testing this issue is purely happening in 2021.2