That could be a lot of things. With a laundry room over top you can have a drain line as well as water lines lined up going down through a plumbing wall, as well as electrical. Honestly I hate stud finders personally. You can always take a drill bit or screw and run it in slowly and see if it hits something, if not use the anchors. Or just try to mount where there's nothing in that area. The other option is cut it open and see what's actually there. If you use anchors you can get ones with screws that are short enough to not hit anything after testing the depth with something like a drywall screw or just a small drill bit. Make a mark on the bit or screw so you know the depth that it's going to run in when utilizing the mount and if you don't hit anything in that depth you're good to use it in that location. If you can't find a spot that satisfactory just mounted on a piece of board and move on