I also love the addition of dedicated streaming service pages, however, while the banners don’t look that bad on the web, they look awful on the Apple TV.
The main standout issues I see are pretty simple to fix tbh:
Negative Space
There is simply too much of it, the background art has been crammed in the corner with a very bad gradient to “blend” it together. You already have a black gradient for the text, at this point you may as well just fill the entire box with the background image.
Width/Padding
It’s too wide. When you hover over it, the size gets bigger (expected) but you’ve not taken into account the padding. Currently, it leaves little to no padding on the far right of the screen in comparison with the left side due to the sidebar.
Hover
I’m pretty sure the banner hover animation is waaay to big in comparison to the rest of the items. Not proud of this, but I actually measured it. Going by the first item in a hub, the banner actually gets a lot closer to the icons in the sidebar than the posters.
Learn More
This text is redundant no? You don’t include this kind of text on anything else, so why would you need it here? The box is interactive and anybody that uses plex would automatically assume you can click on it.
Synopsis
I’m happy with having this here, but the width is also a little too wide. It should still be wider than what we see on normal items, but not that wide.
Ratings
What was the design decision to not include any ratings on this element? Such as Rotten Tomatoes and the other sources you have? Even the age rating would pretty useful here 
Sorry if they sound a little nit-picky, but the designer in me can’t look past the imperfections. Like, the main reason I use Plex is because it has the better UI/UX 