When reached out for comment, a Google spokesperson told ZDNet the ban on VPN ads in China isn't a new development.
"This is not new," the spokesperson said. "We have long-standing policies prohibiting ads in our network for private servers, in countries where such servers are illegal. All advertisers have to comply with local law."
However, the company didn't answer our questions directly, if the ban was put in place on Google's own decision or after a request from Chinese officials.
The Chinese government has been on an all-out war against censorship-thwarting software, such as web proxies and VPN apps, for years.
The Chinese state recently tightened its grip on the local VPN landscape in January 2017, when it started requiring that all VPN providers active in China register for an authorization from the Chinese government.
Nonetheless, Chinese officials are now using the ban to go after users caught using VPNs. The first fine for using a VPN product was issued earlier this year to a Guangdong.
Despite banning consumers from using VPN apps, China remains one of the top sellers of VPN technologies. A November 2018 study found that almost 60 percent of the top free mobile VPN apps are run by companies with Chinese ownership or based in China.