I have always wondered, how do people find the backgrounds in their maps? It seems like whenever I find a background and decide to use it, it just becomes very blurry and its on a different part of the picture then what I want.
They search the image probably from the listed above and others, which has a higher resolution instead of the one that you'd found on a google search or not from the source/original image
And then, they crop the image to 16:9 aspect ratio of the part that they like/prefer from the image
If you found a bg from Google Images, I'd extremely suggest doing reverse search, that way you can not just find the original with the resolution you need but also know the artist to credit them when it's due as well.