Twitch is more than a little jittery about copyright, and that's having an effect even for events where you'd think it would be safe. Metal Injection and Variety report that Twitch abruptly cut off and dubbed over Metallica's BlizzCon 2021 performance (not pictured here). As "Enter Sandman" got underway, the streaming service abruptly replaced the performance with a wildly out-of-character, accordion-driven folk piece — hilarious, but probably not what you were hoping to hear from James Hetfield and crew.
It's not surprising that Twitch would squelch Metallica's performance. Streamers on the service received a flood of DMCA takedown requests in spring 2020 over music, some of them for videos that were years old — Twitch risked one of its own, even though it clearly had permission to air BlizzCon. There's certainly a degree of irony to Metallica being caught up in copyright woes after the band helped lead the crusade against Napster at the turn of the century (its views have evolved since then).
Even so, the incident illustrates the effects the DMCA and aggressive music labels have had on livestreams. Even Twitch, with permission to broadcast BlizzCon, wasn't willing to risk a legal battle over a live gig that theoretically would have been safer than playing an album cut. You could see more tragicomic responses like this until there are either digital copyright reforms or changing attitudes at music labels.