Because Twitch takes massive action against ad blockers.
Twitch is even so persistent that there are special add-ons only for this - but many no longer work because Twitch, as I said, takes massive action against it.
The easiest would be a VPN. Possible locations without advertising: Russia, Mexico or Ukraine. Just try different locations if the ones mentioned don't work.
Otherwise you have to change trains. Then go e.g. This addon: https://addons.mozilla.org/.../twitch_5/
Or possibly also:
If you don't even allow a streamer or the platform to watch monetary advertising, why are you watching?
Twitch takes action against Addblock.
I didn't say that I wouldn't allow the streamers anything, I just care why it doesn't work
Franzhartwig has already given a really good answer, which is why sometimes advertising is not blocked or the ad blocker is recognized
