In the recently released China: Mosques Shuttered, Razed, Altered in Muslim Areas report from Human Rights Watch, we learn that:
The Chinese government is significantly reducing the number of mosques in Ningxia and Gansu provinces under its “mosque consolidation” policy, in violation of the right to freedom of religion, Human Rights Watch said today.

Chinese authorities have decommissioned, closed down, demolished, and converted mosques for secular use as part of the government’s efforts to restrict the practice of Islam. The authorities have removed Islamic architectural features, such as domes and minarets, from many other mosques.
This appears to be part of a larger campaign reportedly detailed in an earlier official document:
“Mosque consolidation”[1] is referenced in an April 2018 central CCP document that outlines a multi-pronged national strategy to “Sinicize” Islam, or make it more Chinese.[2] It instructs the CCP and state agencies throughout the country to “strengthen the standardized management of the construction, renovation and expansion of Islamic religious venues.” The document notes that a central principle behind such “management” is that “there should not be newly built Islamic venues,” in order to “compress the overall number [of mosques].” While there can be exceptions, the document states that “there should be more [mosque] demolitions than constructions.”