Twitch changed the rules for how streamers could do sponsored content. Banned any kind of baked in audio or video ads, banner ads, etc. Also didn’t allow any branding (of the streamer or a sponsor) to cover more than 3% of the screen space meaning that streamers couldn’t have a logo with their name or other socials on the stream.

These changes came almost immediately after they announced new advertising tools, so it seems like they’re trying to force streamers to advertise in a way that they get a cut of the advertisement revenue.