There are two ways you can increase the screen contrast to make items easier to see in the Apple TV app.
Go to the Apple TV app 
on your smart TV, streaming device, or gaming console.
Open the sidebar, then select Settings.
Go to Accessibility > Display, then turn on Reduce Transparency.
Go to the Apple TV app on your smart TV, streaming device, or gaming console.
Open the sidebar, then select Settings.
Go to Accessibility > Display > Focus Style, then choose High Contrast.