I don't understand why they feel the need to hide it.

I can liken my opinion on it to that of Generative AI: Consumers have the right to be informed. Hiding whether AI was used (or SBI/other similar agencies in this case) is not a good look. If a consumer doesn't want to buy games that SBI has worked on, it is the consumer's right to know if a game has been worked on by SBI so they can make an informed decision. In just the same way a person would want to know if Generative AI was used in a game, some consumers want to know if SBI or other similar companies were used during a game's development. And this of course works opposite too. If someone wanted to buy a game specifically because SBI worked on it (which I personally can't see being a real reason to buy a game, but to each their own) then they too should be able to be clearly informed on the matter.

Basically, hiding something like that is anti-consumer. It gives the impression that the developers are trying to trick consumers into buying something they don't want.

For example, if there was a video game which directly funded something you didn't like, let's say something like directly funding Russia's war against Ukraine, you would want to know that before you bought the game, right? When you find out where your money went, you probably wouldn't be very happy, would you? If you had known that information before you bought the game, that likely would have changed your decision to buy the game, right? Now of course, war is a bit more extreme compared to social politics, but the idea is the same. You would feel tricked. You would feel upset. Its the same idea. Consumers want to be informed, and hiding information from consumers is not friendly to consumers. The developers should have just updated the game description to include that SBI worked on the game and left it at that. The drama would likely not have reached its current level.