This is the second time I noticed, I forgot it before when I saw the Updates tabs were gone. This time, I missed the timing for resolving some issues of a project which I have commit permission.
I relied on the feed of projects I stared. Google Code provided such feed before, but it has gone for two months at least. For now, I subscribed to 4 project feeds: Issues, Downloads, Source changes, and Wiki updates.
I didn't check the starred projects feed because that feed was only return no entries, not a 404, it should be, even the updates function is disabled. So, it never occurred to me that the feed was essentially rendered useless when Google Code disabled Updates function.
There is an issue opened and a discussion thread. They have grown too long, didn't read much of them. But I feel Google developers and other developers are two different species.
Please star that issue if you had also used Project Updates, hopefully they can finally understand some of developers rely on that very much.