There are no changes to the parameters in the .ini file, just the file has been updated. Source control becomes dirty by re-saving the file.
Result:
Update the timestamp of DefaultEngine.ini.
Expect:
Don't update the timestamp of DefaultEngine.ini.
Caused by FPhysicsSettingsDetails, but seems to have been that way since a 2016 change.
UE4Editor-CoreUObject.dll!UObject::SaveConfig(unsigned __int64 Flags, const wchar_t * InFilename, FConfigCacheIni * Config) Line 2393 C++ UE4Editor-CoreUObject.dll!UObject::UpdateSingleSectionOfConfigFile(const FString & ConfigIniName) Line 2614 C++ UE4Editor-CoreUObject.dll!UObject::UpdateDefaultConfigFile(const FString & SpecificFileLocation) Line 2633 C++ UE4Editor-DetailCustomizations.dll!FPhysicalSurfaceList::RefreshPhysicalSurfaceList() Line 166 C++ UE4Editor-DetailCustomizations.dll!FPhysicsSettingsDetails::CustomizeDetails(IDetailLayoutBuilder & DetailBuilder) Line 294 C++ UE4Editor-PropertyEditor.dll!DetailLayoutHelpers::QueryCustomDetailLayout(FDetailLayoutData & LayoutData, const TMap<TWeakObjectPtr<UStruct,FWeakObjectPtr>,FDetailLayoutCallback,FDefaultSetAllocator,TDefaultMapHashableKeyFuncs<TWeakObjectPtr<UStruct,FWeakObjectPtr>,FDetailLayoutCallback,0> > & InstancedDetailLayoutMap, const TBaseDelegate<TSharedRef<IDetailCustomization,0> > & GenericLayoutDelegate) Line 400 C++ UE4Editor-PropertyEditor.dll!SDetailsViewBase::UpdateSinglePropertyMap(TSharedPtr<FComplexPropertyNode,0> InRootPropertyNode, FDetailLayoutData & LayoutData, bool bIsExternal) Line 400 C++ UE4Editor-PropertyEditor.dll!SDetailsViewBase::UpdatePropertyMaps() Line 362 C++ UE4Editor-PropertyEditor.dll!SDetailsView::PostSetObject() Line 910 C++ UE4Editor-PropertyEditor.dll!SDetailsView::SetObjectArrayPrivate(const TArray<TWeakObjectPtr<UObject,FWeakObjectPtr>,TSizedDefaultAllocator<32> > & InObjects) Line 663 C++ UE4Editor-PropertyEditor.dll!SDetailsView::SetObjects(const TArray<UObject *,TSizedDefaultAllocator<32> > & InObjects, bool bForceRefresh, bool bOverrideLock) Line 412 C++
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-84265 in the post.