Yeah it's completely unreliable as they have a vested interest in making it appear as though they made a loss much of the time.
They also don't count major income sources like merchandising deals, which can generate several times more than the box office revenue. Franchises like star wars and the MCU generate billions from toys, games, etc.
I instantly hate any movie where I can see that they introduce a character that would be easy to assemble in a factory assembly line.
Like always within the first 20 minutes of one of these movies they introduce a side character like "this is round thing and his eyes glow when he's angry." Or " that guy over there, that's OlafD2 the cuddle pillow that vibrates when danger is near."
I read a while back that studios fudge numbers to make it look like they lost money on movies, or make it look like they made less overall. This way they can get tax cuts and not pay royalties until the movie has made money.