Since July, App Store Connect asks whether your app has social media capabilities. From September, you can't submit a new app or an update without answering.
Apple posted on 9 July that the age rating questionnaire now includes questions about social media capabilities, and that "beginning in September 2026, responses will be required when submitting new apps or updates to the App Store, or when submitting apps for notarization for alternative distribution." September ends tomorrow, so if you have a build in flight, this is the week you meet it.