As Parta.org reports, the change in visa rules was caused by a serious shortage of qualified personnel in these specialties. This year and last year, the volume of H-1B visas issued to qualified workers was exhausted already in April, immediately after they began to be issued. Because a diploma of a degree is required to obtain them, those students who graduated after April were deprived of the opportunity to extend their stay in the United States.
Therefore, American high-tech companies, constantly expressing dissatisfaction with the shortage of qualified personnel, lobbied the U.S. Congress to increase the time for foreigners who graduated from American universities in fields related to exact sciences, natural sciences, technology, and engineering to obtain this type of visa.