Code Y is not a box on Form 1099-R. It's a new distribution code that can be used in box 7 together with another distribution code, such as 7 or 4.
As fanfare said, distribution code Y is new for 2025. The IRS instructions for code Y are very brief and very vague. There are a lot of possible complications that the instructions do not cover, and a lot of unanswered questions. The IRS is probably going to have to issue additional guidance for using code Y before the end of the year. All of us, including the TurboTax software developers, will have to wait for that additional guidance. I'm sure that TurboTax will provide a way of entering QCDs that were not reported with code Y (as it does for 2024 and earlier years, where code Y does not exist). I'm also sure that there will be a lot of confusion, rough edges, and possible bugs since it's new, and the IRS instructions are inadequate.
