Variable stars or variable sensitivity CCDs?

http://legacysurvey.org/viewer?ra=150.1847&dec=14.1075&zoom=14&layer=decals-dr7

Check out this small group of objects…

Screenshot 2019-01-21 at 18.55.05.png
Screenshot 2019-01-21 at 18.54.46.png

the object at top left in the cutouts varies in brightness compared to the central star, and there are two other objects that appear in the second cutout…