Let us submit support tickets about the browser video player
Just a few moments ago, I switched streams and the playback window was an inch too big: There was a field of empty black space between the chat scroll and the player where there wasn't one before. Since I hadn't updated my browser or changed it or anything like that, and further hearing other users complain about it, I decided that Twitch must have rolled out some new feature that wasn't playing nice with me. Heading over to the support ticket page, and after scrolling through the numerous options of permitted support ticket topics I couldn't find anything even close to being about 'Hey your player broke', outside of specific App types I'm not using. It's not an extension either, since neither streamer used extensions.
Why are you not accepting bug reports about what must be the primary way users view content on Twitch? This seems like a tremendous oversight. If the thing is broken, let me tell you and ask for help!
So sorry for the trouble you've had with reporting issues. We have a particular system in place to track issues with video performance: please click on the cog wheel located in the bottom right corner of the video and select Report Playback Issue. The system will route a report to the relevant team accordingly. Thank you!