Metal Editor has multiple views and each of them has a separate queue for GPU command buffer submission.

Last time I tested the behavior years ago, it seems the submitted command buffers were still finishing in submission order despite multiple queues,
but seems something might have changed recently.

Metal uses the command buffer completion handler/framecounter tracking to figure out latest safe resource, so if submissions are finished out of order in some situations, it can cause one-off geometry explosions to happen when repainting the views, typically outside of playmode, but known to cause occasional instability issues with SRP graphics playmode tests.

During original Metal Editor implementation era (macOS 10.11-10.12), the drivers were super picky on how to implement updates for multiple Metal layers, resulting into kernel panics otherwise. I quickly tested the possibility of using a single command queue on current OS, but seeing overall worse performance than with multiple queues