Unfortunately, it is not possible to verify the claim because the statements from official sources are contradicting each other.
Nigerian Foreign Affairs Minister Geoffrey Onyeama also tweeted about the issues faced by Nigerians and other Africans in China regarding COVID-19 pandemic. Later, he clarifies that he had discussed the issues with Zhou Pingjian, the Chinese ambassador to Nigeria.
In a press conference, Chinese Foreign Ministry spokesperson Zhao Lijian denied the allegations stating that Africans were facing discriminations in China. He mentioned that China and Africa are good friends, whereas the African citizens in China were safe. Moreover, the local authorities were observing the concerns of some African nationals in Guangdong Province and had adopted new measures for their safety. He said the Chinese have zero tolerance for discrimination repudiating the claim of differential treatment.
Thus, we cannot objectively verify the statement, because the news releases from the official sources are different from each other, and there is no other credible source available as of 2 May 2020 to accurately verify the claim.
The COVID-19 pandemic has given rise to a lot of potentially dangerous misinformation. For reliable advice on COVID-19 including symptoms, prevention and available treatment, please refer to the World Health Organisation or your national healthcare authority.