YouTube has a weird legacy feature that lets certain channels set up redirects to other channels (but can be pretty easily cheesed to redirect to arbitrary paths, like the subscription confirmation URL). This, combined with another legacy feature, non @handle, channel URLs (/c/username, which can be shortened to /username), is being abused to set up redirects on commonly mistyped URLs. People buy/hack old accounts that have these features available/have valuable channel URLs and use them like this.

There's a whole underground world of social media account trade for this.