Debating with SpringBoot and FastAPI for an internal tool that uses

We're a team of 2 people building an internal website for a company of 10-15 people, it has authentication features and automated payment features/banking related data & operations using our Bank's API.

Both of us are more at ease with Python and FastAPI in general, we've did very minimal SpringBoot in our lives.

My concern is that the website is the banking part, which is a security risk I've never dealt with and I've heard SpringBoot is more equipped for "Bank" stuff.

The last thing I want is leaks, hacks, scams or payment issues because of security breaches or flaws in the security system.

Although I know you can technically setup every framework to be as safe as the next framework, I'm taking into count that we're only a team of 2 devs with minimal experience in one of these frameworks (SpringBoot).

Any realistic advice?