As of my last knowledge update in September 2021, there were 12 major PSBs in India.1
References
1Shah DR, Rao DKB. Asset liabilityy management practices and NPA trends in Indian public and private sector banks. International Educational Journal of Science and Engineering. 2023;6(5). Accessed March 19, 2024. https://iejse.com/journals/index.php/iejse/article/view/49