Thanks for the notice @someguy123
When I started up my new witness nodes I didn't want to take anything on chance so I've allocated a fair amount of memory to the blockchain.
My two witness nodes are running with the setting
shared-file-size = 21G
I can currently see that they are using around 8.8G for the shared_memory file, and that's probably why some nodes crashed when the file grew larger than the allocated space.