The U.S. Patent and Trademark Office (USPTO) is seeing an exponential rise of patent application withdrawal over the past couple of years.
Often the applicant failed to pay the issue fee which leads to patent grant withdrawal. Alternatively, applicant filed multiple other application deriving from the same subject and simply pick the best one to cut down cost. Other case where a court invalidated a different patent for the same treatment by the same company. Similarly, either the examiner or the patent applicant may realize that even though a patent is allowed, due to the discovery of new prior art or other issues, it is not to their best interest to have the patent issued.
However, what is puzzling is that it costs $0 to let a patent with an assigned number issue and >$0 to have it withdrawn there must be a financial incentive to withdraw applications. Either that or patent examiner are getting better at finding prior arts.May 31, 2021