"The same field name is serialized multiple times in the class or its parent class" error is thrown when private variables are declared in the class and its parent class using underscore

How to reproduce:
1. Open the user-attached project “BugReport”
2. Open the “SampleScene” scene
3. Open the “Derived.cs” Asset and add a commented line to trigger the recompilation
4. Observe the Console

Expected results: There are no errors in the Console
Actual result: “The same field name is serialized multiple times in the class or its parent class. This is not supported: Base(Derived) _privateData” error is thrown into the Console

Reproducible with: 2021.3.38f1, 2022.3.28f1, 6000.0.2f1

Reproducible on: Windows 11 Pro, Windows 10 (user’s)
Not reproducible on: No other environment tested

Notes:
-Clicking “Reimport” on the Script doesn’t make the error appear
-Changing the name of the variable in one of the Scripts doesn’t make the error go away

Workaround:
-Deleting the underscore of one of the variables and saving and adding it back solves the issue. However, it reappears after restarting Unity