Why didn't the Qing Dynasty annex the Kazakh region?

In fact, History of the Qing Dynasty also tried to annex the Kazakh region, but it was finally reconciled because of the serious casualties of the officers and men of the Qing army. Historical materials are as follows:

Knowing that Kazakhstan is a nation on horseback, the Qing Dynasty assembled15,000 Mongolian fighters, hundreds of thousands of Manchu cavalry and more than 300,000 Han infantry from the Mongolian tribes who surrendered to the Qing Dynasty. They want to use this 400,000-strong army to sweep the land of Kazakhstan. The Kazakh army is a cavalry, with a total of about160,000 people, and it is also a fierce fighter against Mongolian fighters in the past decade. The generals of the Qing army underestimated the Kazakh army and marched hastily. On the day of the armistice, they found that more than 300,000 people were killed or injured. The Qing dynasty still had a batch of 200,000 troops coming, but the Qing army still had to deal with many enemies, so the Qing dynasty panicked and took the initiative to ask.