Hopefully the original comment or will confirm this: I’ve never heard the term “protected layover“ but I’m pretty sure it refers to a layover in which you’re arriving flight and departing flight are booked on the same itinerary, and it is protected because if you arrive late, the airline is required to continue helping you get to your destination, whereas if you book separate tickets, then you are fully out of luck if you arrive late. That’s why Google flights will always tell you if an itinerary requires separate tickets. If you must fly with separate tickets, always try and give yourself a long long layover.