Why did giant pandas become endangered?

well because they eat a lot of food and their environment changes, get hunted for their fur or died from unknown causes
Giant Pandas are endangered due to poaching and deforestation.

Also, they are becoming endangered because there is a shortage of bamboo, and their habitat has become fragmented, making breeding difficult, and travel between bamboo forests almost impossible.
The giant pandas became endangered, because its habitat was destroyed with new buildings being built, so they have no food or shelter to survive in the wilderness.

well, Giant pandas are threaded mostly by man (hunters) for there fur or mistaken for another animal
because thay have no food left in the wild and the food that pandas eat are bamboo. They take months to grow so they don't have enough food or shelter because people are chopping down their land. That's why they are in danger.

I hope you are satisfied with my answer.

yes