Windows: how to override malloc / free / new / delete globally ?

The simple following program crashes if linking against snmallocshim-static (MSYS2, with clang64 but reproducible on any other MinGW environment):

main.cpp:

#include <QObject>

int main(int argc, char *argv[]) {
    delete new QObject;
    return 0;
}

$ clang++ main.cpp  \
   -I/clang64/include/qt6/ \
   -I/clang64/include/qt6/QtCore \
   -std=c++20 \
    /clang64/lib/libQt6Core.dll.a \
    libsnmallocshim-static.a \
   -lbcrypt -rdynamic

$ lldb ./a.exe
(lldb) r
Process 19300 stopped
* thread #1, stop reason = Exception 0x80000003 encountered at address 0x7ffbd2e9ca82
    frame #0: 0x00007ffbd2e9ca83 ntdll.dll`RtlIsZeroMemory + 163
ntdll.dll`RtlIsZeroMemory:
->  0x7ffbd2e9ca83 <+163>: jmp    0x7ffbd2e9ca91 ; <+177>
    0x7ffbd2e9ca85 <+165>: movq   0xf8(%rsp), %rdi
    0x7ffbd2e9ca8d <+173>: movl   0x20(%rsp), %ebx
    0x7ffbd2e9ca91 <+177>: movl   %ebx, 0x30(%rsp)

(lldb) bt
* thread #1, stop reason = Exception 0x80000003 encountered at address 0x7ffbd2e9ca82
  * frame #0: 0x00007ffbd2e9ca83 ntdll.dll`RtlIsZeroMemory + 163
    frame #1: 0x00007ffbd2ea5b5a ntdll.dll`__misaligned_access + 1066
    frame #2: 0x00007ffbd2ea5e3a ntdll.dll`__misaligned_access + 1802
    frame #3: 0x00007ffbd2eb1e35 ntdll.dll`__misaligned_access + 50949
    frame #4: 0x00007ffbd2dcc3bc ntdll.dll`RtlGetCurrentServiceSessionId + 4892
    frame #5: 0x00007ffbd2dcb001 ntdll.dll`RtlFreeHeap + 81
    frame #6: 0x00007ffbd016364b ucrtbase.dll`_free_base + 27
    frame #7: 0x00007ff65dd213f0 a.exe`main + 96
    frame #8: 0x00007ff65dd21303 a.exe`__tmainCRTStartup at crtexe.c:259:15
    frame #9: 0x00007ff65dd21366 a.exe`mainCRTStartup at crtexe.c:180:9
    frame #10: 0x00007ffbd134259d kernel32.dll`BaseThreadInitThunk + 29
    frame #11: 0x00007ffbd2deaf38 ntdll.dll`RtlUserThreadStart + 40

thus I assume I am linking something incorrectly and some allocations made with ucrt are free with snmalloc or conversely which then makes ucrt scream.

Start with the minimal main.cpp reproducer and the shown clang++ command in the MSYS2 clang64 environment. Investigate how libsnmallocshim-static.a interacts with Qt6 and the UCRT allocation paths, then verify the correct global override or linking arrangement by rerunning the program without the allocator mismatch crash.