The Tombs of the Qianlong and Kangxi Emperors Were All Robbed; Why is Only the Qianlong's Open to the Public?
Yes, the Yongling of the Qianlong Emperor and the Jingshi of the Kangxi Emperor, located in the Qingdongling of Mulan Valley, Hebei, were excavated by criminals during the turbulent period, and criminals took away the Qianlong's palace. The criminal was a prominent figure of the Republic of China, Sun Dianying, who not only blasted Qianlong's Ten Perfect Old Men but also excavated Cixi's Dingling. As for Kangxi's people, it's not clear, probably due to nearby bandits.
Currently, the Qingdongling, as a well-known tourist attraction, the tombs of the emperor and empress, are only partially open, due to reasons. Please listen to me below for a breakdown.

After the founding of the People's Republic of China, the Qingdongling was established as the Qingdongling Cultural Heritage Management Office, which unified the management of these emperors' and empresses' tombs and gradually opened some areas as tourist attractions. Qianlong's Yongling Palace was prioritized because it was extremely luxurious, with all the interior of the palace was made of exquisite Buddhist carvings, like a super-beautiful and super-luxurious underground Buddhist kingdom, which was very attractive to visit. After the management office cleaned it up, Qianlong and his consort's remains were unified into Qianlong's coffin, and the palace was installed with lighting. The rotten coffin of the concubines were copied and returned to their original positions. In this way, the palace was cleaned and opened.

As for Kangxi's Jingshi Palace, due to land issues, his palace was flooded, the deepest part reached more than 2 meters, and the palace's luxury level was far less than Qianlong's, which was generally not attractive to visit. If it were cleaned, it would take a lot of effort, and the management office probably thought that the cost-benefit ratio would be low, so it wasn't cleaned. Only the original palace door was sealed. Kangxi Emperor and his consort are still soaking in cold water