How to reproduce:
1. Open the attached "1282010 repro" project
2. Open the "Test3" Scene from the Assets folder
3. Make sure that both the Scene window and the Game window are open
4. Enter Play Mode
5. Exit Play Mode
6. Repeat steps 3 and 4 until Unity crashes

Expected results: Unity Editor doesn't crash
Actual results: Unity Editor crashes

Reproducible with: 2018.4.29f1, 2019.4.12f1, 2020.1.9f1, 2020.2.0b7, 2021.1.0a1

Notes:
-The Editor usual crashes after entering Play Mode 5 - 10 times but on earlier versions (2018.4) it takes a lot more attempts to crash
-All the Scenes included in the "1282010 repro" project can reproduce the crash but the "Test3" Scene seems to do it the most consistently and with the least amount of attempts
-Judging by the Stack Trace, the crash seems to be coming from Mono
-The "Map Renderer" Component (from Microsoft MapsSDK) seems to be the one responsible for the crash since disabling it stop the crash from reproducing
-Sometimes the crash occurs without leaving a Stack Trace. In such cases, the last line always is: "* Assertion: should not be reached at ..\mono\metadata\class-accessors.c:73"