Latest Chrome update has changed some UI and I can't figure out how to fix it

Ever since the latest Chrome update there have been a couple of annoyances that bother me when watching and perusing YouTube. I'm very much a novice when it comes to this type of stuff though so excuse my lack of terminology and knowledge. It could very well be a me problem or something I've done or clicked or not clicked on.

Whenever I go into full screen mode (and only in full screen mode), the player UI dims until the video starts playing, then it brightens back up to normal. After the video ends, it dims again and stays dimmed until I exit full screen mode and then it returns to normal.

There was also an untested but closed issue I had involving a thumbnails' metadata UI. I downloaded and unpacked the extension to fix this but it did not work. Then, one day, it did. I didn't question it but was just thankful that it worked. But now it no longer works. There was an Error button on the extensions manager page but I cleared it and reloaded and it still does not work.

I've tried going through the settings and I can not find a solution to these 2 problems. This isn't a big deal at all, just annoyances. But if anyone has some free time and thinks they can help me troubleshoot these issues, I'd be very appreciative.

Start by reproducing both reports in Chrome: the dimmed YouTube full-screen player UI and the thumbnail metadata behavior after unpacking the extension. Inspect the extension manager for errors and trace the relevant player and thumbnail UI entry points. Done means both issues are reproducible, their causes are identified, and focused fixes are verified in Chrome.