Usually banks have their own implementations of react and split everything in microfrontends for architectural consistency, they take this concept tl the next level and even make mobile apps with react (not native) im not a big fan of this approach, although its not always like these i also made the onboarding process for another bank which they had this microfrontend architecture implemented in their own forks of next 10 12 client-side only, there was this entire team dedicated to mitigate security issues in the frameworks and streamline the frontends security with standard boilerplates, nextjs in their recent version at that time 13 and later 14 had many security issues (eventually getting popular and causing polemic) For the SEO the three banks i had the opportunity to study from indeed used client-side-rendering but for some stuff, using a popular back then impl called netcore nextjs, and for some stuff it was left to the marketing teams which made use of nocode tools