I’ve found my AirTag isn’t that brilliant. After checking in at Terminal 2 for my flight to Cairo, my luggage was located in a container adjacent to the terminal. When we taxied out it was still there. I can only guess that the signal does not penetrate baggage containers and aircraft holds.
On arrival at Cairo it still indicated it was at terminal 2. However on my connection to Luxor I checked with an agent using my baggage tag and all was well. My AirTag worked properly when I was in my hotel room. It showed my luggage was located in the middle of the Nile!!!