The opposing idiotting media. Again.
"Aircraft declares an emergency after window and large piece of fuselage blows out"
It's called an emergency exit aka a door. What will probably transpire is that following removal for a routine maintenance check the Type 2 exit wasn't correctly reinstalled and this wasn't picked up by the sign off inspection.
Notwithstanding the fact that the amount of fuselage flex in that area on the extra stretched 737 is further evidence that they should have simply reengined the 757 to make a large capacity single aisle aircraft.
Makes you wonder at what point someone in Boeing asks the 737 team wtf they think they're paid for
Although it's a miracle that Bryanair haven't had a similar incident with their derivative of the Max9. Although they seem to be pretty adept at snapping the wing root braces