This problem occurs quite often, especially if you have an application developed by an inexperienced team using old development or security technologies.

You need to keep an eye on the application all the time, you are, after all, a financial company. I can advise you one company from which we ordered the development of an application for our bank. Contact fintech software development company https://owlab.group/our-expertise/finance-banking. They will help you to solve all your problems, and they also use all the new technologies in development, respectively, the level of protection of the application and all the financial operations that you will have will be much higher.