[Bug 50558] New: ntdll-Dealloc_Thread_Stack cause memory leak for C# game

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50558

Bug ID: 50558
           Summary: ntdll-Dealloc_Thread_Stack cause memory leak for C#
                    game
           Product: Wine-staging
           Version: unspecified
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: major
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
                CC: [e-mail], [e-mail]
      Distribution: ---

I've traced down a memory leak in one game to the ntdll-Dealloc_Thread_Stack in
wine-staging. No other wine versions or staging patches cause such problem.
I've reproduced it on actual wine master branch from github with
`./staging/patchinstall.py ntdll-Dealloc_Thread_Stack`

The game is "Delta's Shadow" released in 2020. Demo is available at
https://zxonline.net/game/deltas-shadow/
Its Windows version is written in C# with SDL.
The memory leaks every time game plays SFX and only in this case. A music
doesn't cause leak. I've asked the author: music is played via SDL and SFX is
played with System.Media.SoundPlayer::Play(). It looks like this class is just
calls PlaySound function from winmm.dll and pass a stream with WAV into it. And
this somehow and ups in ntdll.

So, to reproduce the problem:
1. Install wine-staging
2. Install the demo
3. Launch game in wine-staging
4. Press ALt+Enter to switch the game into a windowed mode and launch Task
manager to see the RAM it consumes.
5. Start pressing W and S keys (Up and Down) in game main menu to produce a
menu item change SFX.

Result:
Game RAM usage grows each time you press the key and don't decrease later.

Expected:
No significant RAM usage change.