Telecom giant Cisco (CSCO) announced Thursday it's pulling advertisements from Google's (GOOG) YouTube platforms for "brand safety," citing "standards" issues with content on the site.

"At Cisco, we would rather not wait for something bad to happen. While Google and Facebook have made some strides to combat the issue, at this time we have pulled all online advertising from YouTube until the platform has met our standards," Cisco Chief Marketing Officer Karen Walker wrote in a blog post, adding that it would continue to share video content on the platform.

"Sensitive issues in the media do sometimes spread faster than the media platforms' algorithms can update, leading to what can be a brand-tarnishing experience…" Walker wrote. "Similarly, some content platforms are not properly monitoring and categorizing the content on their sites as it is posted."

There is a growing fear among investors that advertiser backlash may hurt Youtube's revenues, according to Business Insider, which first reported on the Cisco post. 

Ads from more than 300 companies, including Cisco, were run alongside "extremist content," CNN reported last month. 

Late last year Google apologized to ad clients for allowing ads to appear alongside offensive videos on YouTube as high-profile firms including U.S. wireless carriers Verizon (VZ) and AT&T (T) suspended digital advertising on Google's YouTube and other ad platforms not related to search over concerns that their ads may have run next to extremist videos. 

The British government also suspended its advertising on YouTube after some public sector ads appeared next to videos carrying homophobic and anti-Semitic messages. That prompted a flood of major companies to also pull their ads.

Of course, YouTube isn't alone. Facebook (FB) is facing a plethora of problems related to its ad business, from scrutiny over how its ads profile users to the thousands of dollars Russian trolls spent on ads that were aimed at disrupting the 2016 U.S. presidential electio