"Sign in with Google temporarily disabled for this app" when log in YouTube
Updated (2019/12/13):
Our verification request has been approved by YouTube. Users can now log in to the YouTube service normally.

Original post (2019/12/12):
Since YouTube has made adjustments to the Consent screen, we need to re-acquire the verification from YouTube. The verification may take up to several weeks (from 2019/12/12). During this period, users will not be able to log in to the YouTube service.

We apologize for any inconvenience caused and your consideration will be very much appreciated.