How to reproduce:

1. Create a project
2. Install Unity UI or uGUI from Package Manager
3. Import TMP Essential Resources (Window > TextMeshPro > Import TMP Essential Resources)
4. Open TMP Font Asset Creator (Window > TextMeshPro > Font Asset Creator)
5. Generate Font Atlas using SDF32 Render Mode
6. Observe the result

Actual Result: Generating Font Atlas sometimes results in missing Text Mesh Pro Font Asset glyphs, changed glyphs in Editor’s texts, a crash (~35%) or the Editor shutting down without a crash
Expected Result: Generating Font Atlas works consistently

Reproducible with: 6000.0.61f1, 6000.0.73f1, 6000.3.14f1, 6000.4.4f1, 6000.5.0b5, 6000.6.0a3
Not reproducible with: 2023.1.0a10, 6000.0.60f1 (61dfb374e36f)

Reproduced on: Windows 11
Not reproduced on: No other environments tested

Notes:

• The behavior is very inconsistent and a way to always reproduce a desired outcome was not found but creating a fresh new project seems to increase the crash probability
• Editor also crashes after generating Font Atlas just after reimporting everything
• There had been incidents where Editor crashed untouched a few minutes after reloading the project
• There had been incidents where Editor crashed when closing the project with Font Atlas still being generated

First few lines of the stack trace:
0x00007FFBC9EDF039 (Unity) tlsf_free
0x00007FFBC79E15A0 (Unity) DynamicHeapAllocator::Deallocate
0x00007FFBC79E8CF6 (Unity) DynamicHeapAllocator::TryDeallocate
0x00007FFBC79F2DC0 (Unity) DualThreadAllocator<DynamicHeapAllocator>::TryDeallocate
0x00007FFBC79E9315 (Unity) MemoryManager::TryDeallocateWithLabel
0x00007FFBC79EAB43 (Unity) free_alloc_internal