Strange message “Memory trace upload was successful”

My iPhone 7 just “floated” a message down from the top of the screen, saying: “Memory trace upload was successful”.

what does it mean?

my iPhone keeps restarting itself, ever since I updated it last November to iOS 13.2.3

When the phone has restarted, it searches for phone and mobile data, saying: “Mobile data update failed. Your iPhone cannot make or receive calls or access mobile data until it has been updated”. However, i have the latest iOS (13.3.1) and yet it does this throughout the day. Some days it doesn’t do it at all. Other days (like today) it does it a lot.