Memory is not cleared when calling Graphics.DrawMesh in Play mode while Scene window is visible

Reproduction steps:
1. Open the attached project ("1332428R.zip") and open the "SampleScene" scene
2. Enter Play mode
3. Open Task Manager
4. Switch to the scene view
5. Observe increasing memory usage by Unity editor
6. Exit Play mode

Expected result: Memory usage drops as it was before Play mode
Actual result: Memory used by Unity editor remains the same

Reproducible with: 2019.4.25f1, 2020.3.7f1, 2021.1.6f1, 2021.2.0a16
Not reproducible with: 2018.4.34f1 (multiple nunit errors)