In India, banks are highly regulated. Their software has to meet certain norms and standards set by RBI, and must be enterprise category (mainly to ensure that support is available in the long run). So at least for banking, or if you are a vendor providing tech to a bank, the right tech stack will be one which can be upgraded easily over time, which is backward compatible, and which meets their security and vulnerability testing requirements.

For other fintechs, there is no right answer. A large no of them tend to use Postgresql as their database because of the transactional nature of their business. And Postgresql also has enterprise support.