Repeating empty warnings

I'm getting up to 25 of these empty warnings every time the editor loads or plays. No idea what they are, but they're linked to the terrain in some way I think.
I should add, they only started showing up in Unity 2021.2.x

Code (csharp):

1.  
2. 0x00007ff634a350cd (Unity) StackWalker::GetCurrentCallstack
3. 0x00007ff634a3be29 (Unity) StackWalker::ShowCallstack
4. 0x00007ff63599ddf3 (Unity) GetStacktrace
5. 0x00007ff63602328d (Unity) DebugStringToFile
6. 0x00007ff6351f9fd3 (Unity) TreeDatabase::RefreshPrototypes
7. 0x00007ff6351cf0c0 (Unity) TerrainData::AwakeFromLoad
8. 0x00007ff634a0f52f (Unity) AwakeFromLoadQueue::InvokePersistentManagerAwake
9. 0x00007ff634a0ff9c (Unity) AwakeFromLoadQueue::PersistentManagerAwakeFromLoad
10. 0x00007ff634a10103 (Unity) AwakeFromLoadQueue::PersistentManagerAwakeFromLoad
11. 0x00007ff6349e2912 (Unity) PersistentManager::IntegrateAllThreadedObjects
12. 0x00007ff6349e3387 (Unity) PersistentManager::LoadAndIntegrateAllPreallocatedObjects
13. 0x00007ff6349e7242 (Unity) PersistentManager::ReadObject
14. 0x00007ff633f34bb2 (Unity) PPtr<TerrainData>::operator TerrainData * __ptr64
15. 0x00007ff63522b40b (Unity) TerrainCollider::Create
16. 0x00007ff6347fbdb6 (Unity) Collider::AwakeFromLoad
17. 0x00007ff63522adb9 (Unity) TerrainCollider::AwakeFromLoad
18. 0x00007ff634a0f52f (Unity) AwakeFromLoadQueue::InvokePersistentManagerAwake
19. 0x00007ff634a0ff9c (Unity) AwakeFromLoadQueue::PersistentManagerAwakeFromLoad
20. 0x00007ff634a10103 (Unity) AwakeFromLoadQueue::PersistentManagerAwakeFromLoad
21. 0x00007ff634660858 (Unity) LoadSceneOperation::CompleteAwakeSequence
22. 0x00007ff6346612d2 (Unity) LoadSceneOperation::CompletePreloadManagerLoadSceneEditor
23. 0x00007ff634661e7b (Unity) LoadSceneOperation::IntegrateMainThread
24. 0x00007ff634665a71 (Unity) PreloadManager::UpdatePreloadingSingleStep
25. 0x00007ff63466604f (Unity) PreloadManager::WaitForAllAsyncOperationsToComplete
26. 0x00007ff635836372 (Unity) EditorSceneManager::RestoreSceneBackups
27. 0x00007ff635836979 (Unity) EditorSceneManager::RestoreSceneManagerSetup
28. 0x00007ff635830e1b (Unity) EditorSceneManager::LoadLastSceneManagerSetup
29. 0x00007ff63555695e (Unity) RestoreLastOpenedScenes
30. 0x00007ff635549201 (Unity) Application::FinishLoadingProject
31. 0x00007ff6359a858c (Unity) WinMain
32. 0x00007ff636cc01de (Unity) __scrt_common_main_seh
33. 0x00007ff915b57034 (KERNEL32) BaseThreadInitThunk
34. 0x00007ff9171e2651 (ntdll) RtlUserThreadStart
35.