https://www.chess.com/lessons/view/5191
In the lesson linked above, after playing the move Be4, it states "White now has the choice of two pieces to capture, but capturing either one loses material!".
However, they only show the line Qxe4+, where it's more clear to me how white loses material. Why will white lose material on Qxb3 (taking the knight instead)?
The engine doesn't even recommend to play the first move Be4. Can someone help me understand the position further? Thank you
When I ran it

, the computer preferred Be4.

When you try 2 Qxb3, the queen gets trapped:

https://www.chess.com/lessons/view/5191
In the lesson linked above, after playing the move Be4, it states "White now has the choice of two pieces to capture, but capturing either one loses material!".
However, they only show the line Qxe4+, where it's more clear to me how white loses material. Why will white lose material on Qxb3 (taking the knight instead)?
The engine doesn't even recommend to play the first move Be4. Can someone help me understand the position further? Thank you