Inside the ‘arms race’ between YouTube and ad blockers / Against all odds, open source hackers keep outfoxing one of the wealthiest companies.::YouTube’s dramatic content gatekeeping decisions of late have a long history behind them, and there’s an equally long history of these defenses being bypassed.
There is no way to determine if the request comes from an alternative frontend or a legitimate user. Even if they start blocking all public instances of alternatives, which is highly unfeasible since most of them use VPN and blocking all VPNs is extremely restrictive for legitimate users too, you can host them locally.