Actually the history of this app is a little more complicated. In the early 1990s, Citibank decided to establish an outsourced software development group in India to rewrite their banking software from scratch–they established it as a subsidiary company called iFlex. From 2005 onwards, Citibank progressively sold a majority of its stake in iFlex to Oracle, who then renamed the company Oracle Financial Services Software (OFSS). OFSS is listed on the Mumbai stock exchange, but Oracle owns the majority of its stock.
So, rather than being a product which Oracle developed themselves and sold to Citibank, this is actually in some ways the opposite – a product Citibank developed themselves and sold to Oracle.
I used to work for Oracle. I never worked on OFSS software directly, but I did work on an implementation project for some of it. I never saw the internal banking UI, all I ever saw was backend stuff – LDAP, BPML, JVMs, databases, load balancers, firewalls, etc. Indeed this article is the first time I've seen that particular UI in my life. But I can tell from the visual appearance that it is not one of Oracle's more recent UI development frameworks. (I don't know if this is because Citibank is running an older version, or if there are parts of the product still running on a legacy UI framework.)