It's called the Horizon Effect. Computer stops thinking after Qb5+ Bd7. Had it looked two ply deeper, then it would have noticed black can always capture the queen, but it has to stop somewhere.
It's a limitation of computer chess. Of course, if you actually were to play the computer, it would also spend time thinking before making his next moves, and then it would be able to see it coming and avoid it. But just letting it think over a position at move 7, it may well give a line that turns out to blunder a queen on move 13.
Most of the time though, that doesn't mean that the first move of the line is a blunder. But the deeper in the line you get, the less trustworthy it is. At the end of the line it has literally seen 0 moves ahead.
Edit: Also, there's not much they can do about it. Let the computer think for twenty times longer (costs twenty times as much) and then it'll be able to look 1 ply deeper.
Has anyone notice that the computer analysis frequently suggests LOSING variations? And one guy has a blog post about a perfect game according to chess.com computer... better think again!
I've notice this is more than a few of my games I've submitted for analysis. I did email technical support and the reply was "computers mess up sometimes... they aren't perfect." Are you serious!
Here is just one example. Check out the movelist/ suggestion for move 7! g4 was a stronger move, but then it continues with an inferior suggestion of Qb4 and Qb5+ which flat out loses a queen! I double checked it over and over and I'm sure this is losing. This has happened way too often. I hope by putting it in the public something will be done. I especially hate bad customer service... especially when I feel that the founder is a good guy and wouldn't tolerate it. Members pay for this option and the response was disappointing. A simple, "we are working on it," would have sufficed.