Unless you mess with feature flags uBO doesn't work on mainline Chrome/Chromium anymore because Google officially dropped Manifest v2 support. (And thus they can kill the involved feature flags and patch out the code any moment they want).
The only way to more or less reliably use uBO is by installing Ungoogled Chromium, because the minute Google completely patches out Manifest v2 support they will patch it back in.
An alternative option for this is uBlock Origin, with some custom filter rules from the wiki for the uBlockOrigin subreddit.
https://old.reddit.com/r/uBlockOrigin/wiki/solutions/youtube
Unless you mess with feature flags uBO doesn't work on mainline Chrome/Chromium anymore because Google officially dropped Manifest v2 support. (And thus they can kill the involved feature flags and patch out the code any moment they want).
The only way to more or less reliably use uBO is by installing Ungoogled Chromium, because the minute Google completely patches out Manifest v2 support they will patch it back in.
Might be better to use a browser that respects its users by allowing them to install uBO, like Firefox.
uBO quit working on mainline Chromium a few months back.
There's a little feature flag command line trickery to toggle Manifest v2 which should still work on mainline 140+ onwards.
According to the source code and Gerrit this hasn't been patched out yet:
--disable-features=ExtensionManifestV2Unsupported,ExtensionManifestV2Disable
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