
Given the deprecation of MV2 and the advent of MV3, it's very possible that code which deal with launching extensions is being refactored in Chromium, such that this causes uBO to be ready later. Seems to me like it started after the last chrome update. Start using YouTube to see that you are now able to skip ads as other users who are not using Adblock are able to. Disable it by clicking the Disable button and restart your browser if prompted. Of course the best approach is to use Firefox. about:addons Navigate to the Extensions or Appearance panel and try to locate the AdBlock Extension.

Once uBO is all ready, the issue should not be present when opening Youtube in a new tab. Typically this should be well under a second (for example, I get 235 ms in my Firefox Nightly setup). You can find how long uBO took to be all ready after launch in the Support pane in the dashboard, the value of allReadyAfter in the troubleshooting information. I suspect this could be caused by a variety of factors, like low performance devices, and/or having a lot of other extensions beside uBO.

I have seen reports of uBO taking a long time to be ready at launch, for unknown reasons.

I closed all the tabs again and opened YouTube, and somehow the ads are gone for now.Ĭhromium-based browsers won't wait for uBO to be ready when opening tab(s) immediately after browser launch, and this sounds like this is the issue.
