@booec Same issue here on a 2019 i9 16" MBP. Started happening when I upgraded to 13.5.1 last week and it's been shutting down every time I close the lid, even after only a few seconds. I upgraded to 13.5.2 a couple days ago but that hasn't helped.
It's not fully shutting down though, like when I first open it after sleep the trackpad will still have haptic feedback despite the screen being black. I then need to hold the power button until it restarts so I can get the screen working.
I also normally use an external monitor, but this is happening whether it's connected or not. Resetting SMC also did nothing. Hoping it's fixed in an update soon, will update if I find a solution before then.