I'm seeing the same after upgrading to 12.3 beta 1 on 14" MacBook Pro M1 Max. Additionally, sometime I also see an empty narrow Safari window and several of these "The file can't be found" popups. The safari windows doesn't always show up though. I haven't been able to determine a pattern.

I'm seeing the same issue on a MacBook Air M1, on all beta updates since beta 3. Beta 6 still has the same issue. It's not an issue on my 2020 Intel MacBook Pro. Apple, we need a solution for this issue! Hopefully, this is not going to still be a problem when the final version of Monterrey comes out.