YouTube continues its efforts to circumvent ad blockers. Earlier this week, ad blocker SponsorBlock posted that the Google-owned video service is testing out server-side ad injection with a limited number of users.

Essentially, this means that both the ad is injected into the video before it arrives on your device (in contrast to client-side ad injection, where the ads arrive at your device separately), making it harder for software to detect and block the ad.

“This breaks sponsorblock since now all timestamps are offset by the ad times,” SponsorBlock said.

A Google spokesperson seemed to confirm the test in a statement, writing that the service is “improving its performance and reliability in serving both organic and ad video content,” with an update that “may result in suboptimal viewing experiences for viewers with ad blockers installed.”

Google reiterated its position that ad blockers “violate YouTube’s Terms of Service” and that viewers who want an ad-free experience should sign up for YouTube Premium.

This is just the latest move in an ongoing battle, with YouTube constantly finding new ways to get around ad blockers and the ad blockers then trying to adapt. In fact, the company rolled out a pop-up message last year that essentially prevented visitors from watching videos on YouTube unless they disabled their ad blockers.

When I spoke to the companies behind several ad blockers last fall, Ghostery’s director of product and engineering Krzysztof Modras told me that “as one of the world’s largest publishers, YouTube constantly invests in circumventing ad blocking” and that it “seems to be adapting [its] methods more frequently than ever before.”

More recently, an email from another ad blocker, AdGuard, suggested that while the server-side approach is new to YouTube on the web, the service has already been doing something similar in its mobile apps. 

AdGuard said it remains “optimistic that solutions will emerge, albeit requiring concerted efforts and innovative approaches from ad-blocking developers and ad filtering community.”