The provision is infamously toothless. A proper DMCA notice (yes, you can send improper ones...) is supposed to contain a statement made under penalty of perju

The provision is infamously toothless. A proper DMCA notice (yes, you can send improper ones...) is supposed to contain a statement made under penalty of perjury saying you are or represent the owner of the allegedly infringed upon work. So you just have to own the thing you claim is infringed, you do not have to be correct that the items you target with the notice are actually infringing upon your work. That stops me from claiming to own Mickey Mouse and sending notices against it. It does not stop me from claiming something I actually own copyright to and sending spurious notices to non-infringing works. Now, there might be some minor monetary liability for costs incurred by a completely bogus notice, but they're probably not large enough to sue over without ending up losing more money on the suit than you win in most cases, so it's relatively untested, though I think there may have been a settlement or two over such claims.