YouTube is currently running “a small experiment globally” that blocks viewers from watching videos on the platform with ad blockers enabled.

For those unaware, the recent crackdown trails YouTube’s previous “small experiment” carried out in May, during which the Google-owned platform started directly blocking ad blocker users from accessing the site.

The new feature in testing was first discovered by a Redditor Reddit_n_Me on Wednesday, who spotted a popup message from YouTube when trying to watch videos with an ad blocker enabled.

The pop-up notification requests the user to turn off the ad blocker, or else they will be banned from YouTube viewing after watching three videos with an ad blocker enabled.

“Video player will be blocked after 3 videos. It looks like you may be using an ad blocker. Video playback will be blocked unless YouTube is allow listed or the ad blocker is disabled,” the message reads.

“Ads allow YouTube to stay free for billions of users worldwide. You can go ad-free with YouTube Premium, and creators can still get paid from your subscription.”

After receiving this warning, YouTube users are presented with two options, which are either to disable their ad blocker and allow YouTube ads (or) subscribe to YouTube Premium to watch videos without ads.

Previously, YouTube only showed popups to ad blocker users, reminding them that ad blockers violate the company’s Terms of Service (ToS).

YouTube has confirmed to BleepingComputer that the new alerts are part of an experiment, and the company urges viewers to allow ads on the platform or try YouTube Premium.

“We’re running a small experiment globally that urges viewers with ad blockers enabled to allow ads on YouTube or try YouTube Premium,” YouTube said in a statement to BleepingComputer.

YouTube also said that playback might be temporarily disabled in “extreme cases” where viewers continue their use of ad blockers.

“We take disabling playback very seriously, and will only disable playback if viewers ignore repeated requests to allow ads on YouTube. To prevent disruption as part of this experiment, viewers using ad blockers may disable their ad blocker, allow YouTube ads or subscribe to YouTube Premium,” the company explained.

It also added, “In cases when viewers feel they have been falsely flagged as using an ad blocker, they can share this feedback by clicking on the link in the prompt.”

Currently, this new YouTube test affects a small number of users. However, the Google-owned platform did not reveal how many people and what regions were part of the experiment. It is also unclear how viewers who are blocked from watching would be able to re-access the site.