I think i'm running into a similar problem as you did. Did you ever find out how to fix this without having to disable Metal API Validation?

Simply disabling Wifi and Bluetooth does make it a lot quicker to launch but this is really not a long term solution, especially when you're debugging apps that require a network connection or even debugging your bluetooth code. This would mean that your workflow becomes: disable bluetooth, launch app, enable bluetooth and debug (same for network related code assuming you're not using cellular). It just seems like many steps for something that always worked fine.