There are multiple reports about this phenomenon, but they appear to have originated at Fast Company, which I believe was the first to note that Google stopped updating its iOS apps on December 7. Apple previously explained to developers that they would need to submit privacy information with any new or updated iOS app versions starting on December 8.
“On each app’s product page, users can learn about some of the data types the app may collect, and whether that data is linked to them or used to track them,” Apple explains to its developers. “You’ll need to provide information about your app’s privacy practices, including the practices of third-party partners whose code you integrate into your app.”
The natural assumption here is that Apple’s new requirements to divulge tracking data collected by apps is what’s tripping up Google. After all, Google makes the vast majority of its revenues by quietly tracking its users on mobile and the web and then selling that information to advertisers.
Google hasn’t yet commented on this issue.