Got an email reply from Apple developer saying that, to update age ratings - we do not have to upload binary / submit app for formal review

Thanks for sharing. The reply says when you not update the age rating the app might be removed. That's something new which nowhere was written before.

"may be". quite confusing right?

at least updating age rating questionnaires is very easy and straightforward, and no need to submit new binary - i guess it would be easy.