That strip was taking at a different light situation than the background. It also has a higher resolution. There are many smaller strips and patches on the surface that look similarly out of place.
Google could blend them somehow but I guess much more imagery would be needed to have the average look good.
Also check out the overexaggerated shadowy mess at the poles. :)
Same goes for lots of other places. A few years ago, even the earth map was full with these stripes when Google did not had good images from everywhere. Also check out Pluto, one half of the planet is just a smear.
Note that data from more than one source is combined to make these maps. And, some sites have been studied more closely than others due to lunar mission site selection studies.
Google could blend them somehow but I guess much more imagery would be needed to have the average look good.
Also check out the overexaggerated shadowy mess at the poles. :)