Twitch is doing a thing where it's using its old Surestream tech to inject a 1-3 second bump at the start of each feed.
It's a purple and yellow screen that has vibes of the old Adult Swim bumps. Just text rolling on the screen with silly joking little bumps. Then the actual stream starts.
It comes up instantly so I suspect this is a way to cheat the HLS kickstart lagtime but it delays getting to the content overall and is annoying to boot.
...and will probably turn into how they deliver preroll ads again later on.